periph/spi: Update clock polarity and phase documentation for clarity.
periph/spi: Update clock polarity and phase documentation for clarity.

Signed-off-by: Joakim Gebart <d097f2c6c8fee73e3ea75e1d62412e3886346faa@eistec.se>

openkosmosorg/RIOT,khhhh/RIOT,PSHIVANI/Riot-Code,sumanpanchal/RIOT,ks156/RIOT,MohmadAyman/RIOT,rajma996/RIOT,shady33/RIOT,koenning/RIOT,luciotorre/RIOT,beurdouche/RIOT,zhuoshuguo/RIOT,luciotorre/RIOT,alex1818/RIOT,changbiao/RIOT,lazytech-org/RIOT,Osblouf/RIOT,benoit-canet/RIOT,dailab/RIOT,Yonezawa-T2/RIOT,centurysys/RIOT,MonsterCode8000/RIOT,ntrtrung/RIOT,kbumsik/RIOT,kbumsik/RIOT,ntrtrung/RIOT,neiljay/RIOT,chris-wood/RIOT,centurysys/RIOT,jfischer-phytec-iot/RIOT,rakendrathapa/RIOT,RIOT-OS/RIOT,jferreir/RIOT,Lexandro92/RIOT-CoAP,arvindpdmn/RIOT,ximus/RIOT,Osblouf/RIOT,foss-for-synopsys-dwc-arc-processors/RIOT,rakendrathapa/RIOT,plushvoxel/RIOT,Lexandro92/RIOT-CoAP,rfswarm2/RIOT,kb2ma/RIOT,binarylemon/RIOT,kushalsingh007/RIOT,rousselk/RIOT,kb2ma/RIOT,khhhh/RIOT,rfswarm2/RIOT,lebrush/RIOT,kbumsik/RIOT,RubikonAlpha/RIOT,MonsterCode8000/RIOT,toonst/RIOT,neiljay/RIOT,OTAkeys/RIOT,jhollister/RIOT,zhuoshuguo/RIOT,altairpearl/RIOT,OTAkeys/RIOT,rajma996/RIOT,benoit-canet/RIOT,backenklee/RIOT,yogo1212/RIOT,alex1818/RIOT,wentaoshang/RIOT,gautric/RIOT,gebart/RIOT,malosek/RIOT,dailab/RIOT,khhhh/RIOT,JensErdmann/RIOT,attdona/RIOT,Osblouf/RIOT,latsku/RIOT,ntrtrung/RIOT,aeneby/RIOT,FrancescoErmini/RIOT,foss-for-synopsys-dwc-arc-processors/RIOT,jasonatran/RIOT,watr-li/RIOT,d00616/RIOT,binarylemon/RIOT,kaspar030/RIOT,koenning/RIOT,Ell-i/RIOT,jbeyerstedt/RIOT-OTA-update,robixnai/RIOT,gbarnett/RIOT,RIOT-OS/RIOT,robixnai/RIOT,jfischer-phytec-iot/RIOT,JensErdmann/RIOT,RIOT-OS/RIOT,LudwigKnuepfer/RIOT,Lexandro92/RIOT-CoAP,Ell-i/RIOT,kYc0o/RIOT,stevenj/RIOT,cladmi/RIOT,dhruvvyas90/RIOT,beurdouche/RIOT,josephnoir/RIOT,stevenj/RIOT,ThanhVic/RIOT,josephnoir/RIOT,EmuxEvans/RIOT,abkam07/RIOT,miri64/RIOT,toonst/RIOT,mziegert/RIOT,koenning/RIOT,attdona/RIOT,A-Paul/RIOT,mziegert/RIOT,Darredevil/RIOT,adrianghc/RIOT,gebart/RIOT,openkosmosorg/RIOT,jhollister/RIOT,PSHIVANI/Riot-Code,rousselk/RIOT,FrancescoErmini/RIOT,marcosalm/RIOT,haoyangyu/RIOT,daniel-k/RIOT,centurysys/RIOT,immesys/RiSyn,thiagohd/RIOT,abp719/RIOT,adrianghc/RIOT,aeneby/RIOT,ntrtrung/RIOT,beurdouche/RIOT,TobiasFredersdorf/RIOT,sumanpanchal/RIOT,tfar/RIOT,thomaseichinger/RIOT,hamilton-mote/RIOT-OS,kerneltask/RIOT,chris-wood/RIOT,dkm/RIOT,MohmadAyman/RIOT,syin2/RIOT,daniel-k/RIOT,automote/RIOT,gebart/RIOT,basilfx/RIOT,hamilton-mote/RIOT-OS,kbumsik/RIOT,rfuentess/RIOT,ximus/RIOT,fnack/RIOT,l3nko/RIOT,MohmadAyman/RIOT,kaleb-himes/RIOT,rakendrathapa/RIOT,authmillenon/RIOT,thomaseichinger/RIOT,jfischer-phytec-iot/RIOT,herrfz/RIOT-old,Lexandro92/RIOT-CoAP,avmelnikoff/RIOT,latsku/RIOT,chris-wood/RIOT,phiros/RIOT,MohmadAyman/RIOT,jferreir/RIOT,MonsterCode8000/RIOT,alignan/RIOT,jremmert-phytec-iot/RIOT,abp719/RIOT,jfischer-phytec-iot/RIOT,foss-for-synopsys-dwc-arc-processors/RIOT,BytesGalore/RIOT,jhollister/RIOT,jhollister/RIOT,l3nko/RIOT,attdona/RIOT,tfar/RIOT,immesys/RiSyn,rfuentess/RIOT,smlng/RIOT,alex1818/RIOT,mfrey/RIOT,katezilla/RIOT,kushalsingh007/RIOT,jhollister/RIOT,altairpearl/RIOT,changbiao/RIOT,plushvoxel/RIOT,robixnai/RIOT,d00616/RIOT,plushvoxel/RIOT,RubikonAlpha/RIOT,cladmi/RIOT,x3ro/RIOT,alex1818/RIOT,marcosalm/RIOT,katezilla/RIOT,herrfz/RIOT-old,attdona/RIOT,Lexandro92/RIOT-CoAP,biboc/RIOT,wentaoshang/RIOT,RBartz/RIOT,ant9000/RIOT,authmillenon/RIOT,altairpearl/RIOT,Ell-i/RIOT,syin2/RIOT,OlegHahm/RIOT,shady33/RIOT,kYc0o/RIOT,dhruvvyas90/RIOT,Josar/RIOT,rajma996/RIOT,sgso/RIOT,Ell-i/RIOT,mziegert/RIOT,jasonatran/RIOT,koenning/RIOT,brettswann/RIOT,kb2ma/RIOT,OlegHahm/RIOT,malosek/RIOT,Lexandro92/RIOT-CoAP,binarylemon/RIOT,FrancescoErmini/RIOT,automote/RIOT,biboc/RIOT,thiagohd/RIOT,dailab/RIOT,latsku/RIOT,khhhh/RIOT,patkan/RIOT,neiljay/RIOT,dailab/RIOT,benoit-canet/RIOT,abkam07/RIOT,lebrush/RIOT,thiagohd/RIOT,shady33/RIOT,thomaseichinger/RIOT,zhuoshuguo/RIOT,rfuentess/RIOT,rfswarm/RIOT,marcosalm/RIOT,josephnoir/RIOT,luciotorre/RIOT,abp719/RIOT,abp719/RIOT,attdona/RIOT,rakendrathapa/RIOT,ximus/RIOT,ThanhVic/RIOT,altairpearl/RIOT,jasonatran/RIOT,authmillenon/RIOT,marcosalm/RIOT,tdautc19841202/RIOT,neumodisch/RIOT,tdautc19841202/RIOT,Josar/RIOT,authmillenon/RIOT,abp719/RIOT,ks156/RIOT,gebart/RIOT,haoyangyu/RIOT,gautric/RIOT,LudwigKnuepfer/RIOT,adrianghc/RIOT,malosek/RIOT,roberthartung/RIOT,backenklee/RIOT,latsku/RIOT,FrancescoErmini/RIOT,DipSwitch/RIOT,daniel-k/RIOT,mfrey/RIOT,cladmi/RIOT,jremmert-phytec-iot/RIOT,koenning/RIOT,wentaoshang/RIOT,arvindpdmn/RIOT,wentaoshang/RIOT,DipSwitch/RIOT,patkan/RIOT,kaleb-himes/RIOT,rousselk/RIOT,jferreir/RIOT,dhruvvyas90/RIOT,DipSwitch/RIOT,MonsterCode8000/RIOT,jfischer-phytec-iot/RIOT,Darredevil/RIOT,neiljay/RIOT,l3nko/RIOT,PSHIVANI/Riot-Code,smlng/RIOT,Yonezawa-T2/RIOT,sumanpanchal/RIOT,rakendrathapa/RIOT,benoit-canet/RIOT,tdautc19841202/RIOT,haoyangyu/RIOT,adrianghc/RIOT,Ell-i/RIOT,bartfaizoltan/RIOT,neiljay/RIOT,OlegHahm/RIOT,Josar/RIOT,foss-for-synopsys-dwc-arc-processors/RIOT,gautric/RIOT,brettswann/RIOT,LudwigOrtmann/RIOT,chris-wood/RIOT,rfswarm/RIOT,ntrtrung/RIOT,aeneby/RIOT,openkosmosorg/RIOT,openkosmosorg/RIOT,rousselk/RIOT,avmelnikoff/RIOT,gebart/RIOT,khhhh/RIOT,basilfx/RIOT,kb2ma/RIOT,l3nko/RIOT,smlng/RIOT,l3nko/RIOT,TobiasFredersdorf/RIOT,OTAkeys/RIOT,immesys/RiSyn,gbarnett/RIOT,MarkXYang/RIOT,lebrush/RIOT,openkosmosorg/RIOT,abkam07/RIOT,binarylemon/RIOT,Hyungsin/RIOT-OS,jbeyerstedt/RIOT-OTA-update,x3ro/RIOT,LudwigKnuepfer/RIOT,asanka-code/RIOT,Hyungsin/RIOT-OS,MarkXYang/RIOT,MarkXYang/RIOT,d00616/RIOT,RubikonAlpha/RIOT,patkan/RIOT,MarkXYang/RIOT,herrfz/RIOT,kaspar030/RIOT,dkm/RIOT,stevenj/RIOT,fnack/RIOT,automote/RIOT,alignan/RIOT,herrfz/RIOT-old,wentaoshang/RIOT,shady33/RIOT,ks156/RIOT,wentaoshang/RIOT,kbumsik/RIOT,mziegert/RIOT,neumodisch/RIOT,syin2/RIOT,Yonezawa-T2/RIOT,zhuoshuguo/RIOT,d00616/RIOT,malosek/RIOT,yogo1212/RIOT,miri64/RIOT,LudwigOrtmann/RIOT,neumodisch/RIOT,phiros/RIOT,rajma996/RIOT,hamilton-mote/RIOT-OS,fnack/RIOT,dkm/RIOT,FrancescoErmini/RIOT,Yonezawa-T2/RIOT,luciotorre/RIOT,PSHIVANI/Riot-Code,RIOT-OS/RIOT,msolters/RIOT,MonsterCode8000/RIOT,roberthartung/RIOT,sgso/RIOT,dailab/RIOT,brettswann/RIOT,abkam07/RIOT,brettswann/RIOT,Osblouf/RIOT,x3ro/RIOT,changbiao/RIOT,haoyangyu/RIOT,arvindpdmn/RIOT,haoyangyu/RIOT,miri64/RIOT,adjih/RIOT,thomaseichinger/RIOT,kerneltask/RIOT,A-Paul/RIOT,herrfz/RIOT-old,abkam07/RIOT,shady33/RIOT,binarylemon/RIOT,plushvoxel/RIOT,thiagohd/RIOT,asanka-code/RIOT,Hyungsin/RIOT-OS,bartfaizoltan/RIOT,changbiao/RIOT,abp719/RIOT,fnack/RIOT,roberthartung/RIOT,rfuentess/RIOT,miri64/RIOT,jhollister/RIOT,RubikonAlpha/RIOT,rfswarm/RIOT,dhruvvyas90/RIOT,ximus/RIOT,RBartz/RIOT,mfrey/RIOT,patkan/RIOT,herrfz/RIOT,roberthartung/RIOT,sgso/RIOT,MarkXYang/RIOT,phiros/RIOT,gbarnett/RIOT,ThanhVic/RIOT,beurdouche/RIOT,Darredevil/RIOT,asanka-code/RIOT,cladmi/RIOT,bartfaizoltan/RIOT,foss-for-synopsys-dwc-arc-processors/RIOT,lebrush/RIOT,jremmert-phytec-iot/RIOT,mtausig/RIOT,adrianghc/RIOT,ant9000/RIOT,thiagohd/RIOT,JensErdmann/RIOT,robixnai/RIOT,arvindpdmn/RIOT,watr-li/RIOT,MarkXYang/RIOT,ThanhVic/RIOT,latsku/RIOT,basilfx/RIOT,msolters/RIOT,attdona/RIOT,DipSwitch/RIOT,alignan/RIOT,rfuentess/RIOT,kaspar030/RIOT,thiagohd/RIOT,jferreir/RIOT,patkan/RIOT,latsku/RIOT,LudwigKnuepfer/RIOT,mfrey/RIOT,patkan/RIOT,A-Paul/RIOT,rakendrathapa/RIOT,malosek/RIOT,RBartz/RIOT,DipSwitch/RIOT,BytesGalore/RIOT,smlng/RIOT,Darredevil/RIOT,rajma996/RIOT,tfar/RIOT,katezilla/RIOT,changbiao/RIOT,katezilla/RIOT,avmelnikoff/RIOT,RubikonAlpha/RIOT,MohmadAyman/RIOT,openkosmosorg/RIOT,sgso/RIOT,josephnoir/RIOT,jbeyerstedt/RIOT-OTA-update,RBartz/RIOT,asanka-code/RIOT,EmuxEvans/RIOT,EmuxEvans/RIOT,msolters/RIOT,arvindpdmn/RIOT,Osblouf/RIOT,luciotorre/RIOT,kYc0o/RIOT,kaleb-himes/RIOT,biboc/RIOT,alignan/RIOT,abkam07/RIOT,rajma996/RIOT,adjih/RIOT,adjih/RIOT,TobiasFredersdorf/RIOT,tfar/RIOT,gbarnett/RIOT,luciotorre/RIOT,yogo1212/RIOT,chris-wood/RIOT,msolters/RIOT,altairpearl/RIOT,marcosalm/RIOT,ks156/RIOT,roberthartung/RIOT,rfswarm2/RIOT,TobiasFredersdorf/RIOT,EmuxEvans/RIOT,bartfaizoltan/RIOT,syin2/RIOT,centurysys/RIOT,RubikonAlpha/RIOT,LudwigOrtmann/RIOT,tdautc19841202/RIOT,LudwigKnuepfer/RIOT,brettswann/RIOT,robixnai/RIOT,d00616/RIOT,toonst/RIOT,dkm/RIOT,zhuoshuguo/RIOT,altairpearl/RIOT,automote/RIOT,backenklee/RIOT,immesys/RiSyn,kerneltask/RIOT,RBartz/RIOT,Hyungsin/RIOT-OS,PSHIVANI/Riot-Code,jremmert-phytec-iot/RIOT,benoit-canet/RIOT,miri64/RIOT,marcosalm/RIOT,Hyungsin/RIOT-OS,yogo1212/RIOT,mfrey/RIOT,jbeyerstedt/RIOT-OTA-update,kushalsingh007/RIOT,dkm/RIOT,EmuxEvans/RIOT,malosek/RIOT,rfswarm/RIOT,shady33/RIOT,mziegert/RIOT,alex1818/RIOT,herrfz/RIOT,phiros/RIOT,OlegHahm/RIOT,kerneltask/RIOT,JensErdmann/RIOT,kYc0o/RIOT,ant9000/RIOT,JensErdmann/RIOT,dhruvvyas90/RIOT,OTAkeys/RIOT,LudwigOrtmann/RIOT,kushalsingh007/RIOT,khhhh/RIOT,jferreir/RIOT,watr-li/RIOT,BytesGalore/RIOT,hamilton-mote/RIOT-OS,BytesGalore/RIOT,rousselk/RIOT,chris-wood/RIOT,syin2/RIOT,kaleb-himes/RIOT,jbeyerstedt/RIOT-OTA-update,tfar/RIOT,kaleb-himes/RIOT,gbarnett/RIOT,yogo1212/RIOT,jasonatran/RIOT,RIOT-OS/RIOT,stevenj/RIOT,biboc/RIOT,aeneby/RIOT,ntrtrung/RIOT,fnack/RIOT,msolters/RIOT,OlegHahm/RIOT,asanka-code/RIOT,kYc0o/RIOT,rfswarm/RIOT,avmelnikoff/RIOT,ximus/RIOT,alex1818/RIOT,biboc/RIOT,stevenj/RIOT,x3ro/RIOT,authmillenon/RIOT,automote/RIOT,haoyangyu/RIOT,kaspar030/RIOT,basilfx/RIOT,kerneltask/RIOT,d00616/RIOT,kb2ma/RIOT,mtausig/RIOT,ThanhVic/RIOT,bartfaizoltan/RIOT,arvindpdmn/RIOT,ThanhVic/RIOT,yogo1212/RIOT,herrfz/RIOT,gbarnett/RIOT,alignan/RIOT,tdautc19841202/RIOT,plushvoxel/RIOT,daniel-k/RIOT,mtausig/RIOT,BytesGalore/RIOT,jasonatran/RIOT,Josar/RIOT,TobiasFredersdorf/RIOT,hamilton-mote/RIOT-OS,Osblouf/RIOT,jremmert-phytec-iot/RIOT,kushalsingh007/RIOT,neumodisch/RIOT,fnack/RIOT,OTAkeys/RIOT,dhruvvyas90/RIOT,phiros/RIOT,EmuxEvans/RIOT,LudwigOrtmann/RIOT,jferreir/RIOT,lebrush/RIOT,daniel-k/RIOT,herrfz/RIOT,koenning/RIOT,ximus/RIOT,rousselk/RIOT,immesys/RiSyn,Josar/RIOT,ant9000/RIOT,robixnai/RIOT,sumanpanchal/RIOT,centurysys/RIOT,lazytech-org/RIOT,neumodisch/RIOT,mziegert/RIOT,rfswarm/RIOT,MonsterCode8000/RIOT,toonst/RIOT,stevenj/RIOT,A-Paul/RIOT,avmelnikoff/RIOT,ant9000/RIOT,changbiao/RIOT,DipSwitch/RIOT,ks156/RIOT,backenklee/RIOT,watr-li/RIOT,PSHIVANI/Riot-Code,RBartz/RIOT,toonst/RIOT,A-Paul/RIOT,cladmi/RIOT,msolters/RIOT,herrfz/RIOT-old,daniel-k/RIOT,backenklee/RIOT,josephnoir/RIOT,FrancescoErmini/RIOT,watr-li/RIOT,zhuoshuguo/RIOT,mtausig/RIOT,smlng/RIOT,bartfaizoltan/RIOT,sgso/RIOT,Darredevil/RIOT,lazytech-org/RIOT,Yonezawa-T2/RIOT,katezilla/RIOT,sgso/RIOT,LudwigOrtmann/RIOT,sumanpanchal/RIOT,rfswarm2/RIOT,asanka-code/RIOT,rfswarm2/RIOT,lazytech-org/RIOT,Darredevil/RIOT,lazytech-org/RIOT,Yonezawa-T2/RIOT,JensErdmann/RIOT,mtausig/RIOT,kushalsingh007/RIOT,tdautc19841202/RIOT,immesys/RiSyn,thomaseichinger/RIOT,gautric/RIOT,adjih/RIOT,herrfz/RIOT,kaspar030/RIOT,sumanpanchal/RIOT,automote/RIOT,lebrush/RIOT,brettswann/RIOT,neumodisch/RIOT,aeneby/RIOT,gautric/RIOT,rfswarm2/RIOT,centurysys/RIOT,phiros/RIOT,watr-li/RIOT,authmillenon/RIOT,MohmadAyman/RIOT,basilfx/RIOT,l3nko/RIOT,benoit-canet/RIOT,binarylemon/RIOT,beurdouche/RIOT,x3ro/RIOT,jremmert-phytec-iot/RIOT,adjih/RIOT