boards/nrf51dongle: add xtimer configuration
boards/nrf51dongle: add xtimer configuration

kerneltask/RIOT,lazytech-org/RIOT,FrancescoErmini/RIOT,FrancescoErmini/RIOT,neiljay/RIOT,LudwigKnuepfer/RIOT,yogo1212/RIOT,authmillenon/RIOT,RIOT-OS/RIOT,Yonezawa-T2/RIOT,MohmadAyman/RIOT,OlegHahm/RIOT,kYc0o/RIOT,attdona/RIOT,gautric/RIOT,Hyungsin/RIOT-OS,alignan/RIOT,shady33/RIOT,authmillenon/RIOT,cladmi/RIOT,d00616/RIOT,jremmert-phytec-iot/RIOT,lazytech-org/RIOT,rajma996/RIOT,malosek/RIOT,LudwigKnuepfer/RIOT,beurdouche/RIOT,ant9000/RIOT,kbumsik/RIOT,tfar/RIOT,toonst/RIOT,asanka-code/RIOT,yogo1212/RIOT,attdona/RIOT,jasonatran/RIOT,rajma996/RIOT,rajma996/RIOT,MohmadAyman/RIOT,tfar/RIOT,immesys/RiSyn,kaleb-himes/RIOT,wentaoshang/RIOT,katezilla/RIOT,gautric/RIOT,foss-for-synopsys-dwc-arc-processors/RIOT,rajma996/RIOT,Josar/RIOT,adrianghc/RIOT,FrancescoErmini/RIOT,lazytech-org/RIOT,aeneby/RIOT,mtausig/RIOT,OTAkeys/RIOT,Ell-i/RIOT,FrancescoErmini/RIOT,asanka-code/RIOT,rfuentess/RIOT,neiljay/RIOT,toonst/RIOT,gebart/RIOT,syin2/RIOT,rousselk/RIOT,x3ro/RIOT,dkm/RIOT,LudwigOrtmann/RIOT,TobiasFredersdorf/RIOT,gautric/RIOT,Josar/RIOT,basilfx/RIOT,Ell-i/RIOT,biboc/RIOT,RIOT-OS/RIOT,kb2ma/RIOT,BytesGalore/RIOT,backenklee/RIOT,ant9000/RIOT,beurdouche/RIOT,altairpearl/RIOT,dkm/RIOT,x3ro/RIOT,hamilton-mote/RIOT-OS,dailab/RIOT,backenklee/RIOT,kerneltask/RIOT,katezilla/RIOT,alignan/RIOT,backenklee/RIOT,adrianghc/RIOT,MohmadAyman/RIOT,zhuoshuguo/RIOT,FrancescoErmini/RIOT,kYc0o/RIOT,ks156/RIOT,aeneby/RIOT,hamilton-mote/RIOT-OS,gebart/RIOT,thomaseichinger/RIOT,A-Paul/RIOT,d00616/RIOT,dkm/RIOT,ks156/RIOT,ant9000/RIOT,miri64/RIOT,adjih/RIOT,yogo1212/RIOT,x3ro/RIOT,wentaoshang/RIOT,smlng/RIOT,josephnoir/RIOT,Ell-i/RIOT,rfuentess/RIOT,wentaoshang/RIOT,rakendrathapa/RIOT,mtausig/RIOT,roberthartung/RIOT,roberthartung/RIOT,immesys/RiSyn,plushvoxel/RIOT,adjih/RIOT,d00616/RIOT,adjih/RIOT,immesys/RiSyn,LudwigOrtmann/RIOT,immesys/RiSyn,altairpearl/RIOT,Hyungsin/RIOT-OS,TobiasFredersdorf/RIOT,zhuoshuguo/RIOT,LudwigOrtmann/RIOT,TobiasFredersdorf/RIOT,jremmert-phytec-iot/RIOT,kaleb-himes/RIOT,avmelnikoff/RIOT,neumodisch/RIOT,alignan/RIOT,rousselk/RIOT,mtausig/RIOT,aeneby/RIOT,brettswann/RIOT,avmelnikoff/RIOT,asanka-code/RIOT,yogo1212/RIOT,shady33/RIOT,Hyungsin/RIOT-OS,kaspar030/RIOT,aeneby/RIOT,jasonatran/RIOT,tfar/RIOT,foss-for-synopsys-dwc-arc-processors/RIOT,LudwigKnuepfer/RIOT,syin2/RIOT,jremmert-phytec-iot/RIOT,thomaseichinger/RIOT,LudwigOrtmann/RIOT,MohmadAyman/RIOT,kYc0o/RIOT,jasonatran/RIOT,lazytech-org/RIOT,adrianghc/RIOT,Yonezawa-T2/RIOT,attdona/RIOT,cladmi/RIOT,attdona/RIOT,A-Paul/RIOT,malosek/RIOT,asanka-code/RIOT,zhuoshuguo/RIOT,LudwigKnuepfer/RIOT,rakendrathapa/RIOT,plushvoxel/RIOT,shady33/RIOT,cladmi/RIOT,neiljay/RIOT,alignan/RIOT,malosek/RIOT,ant9000/RIOT,basilfx/RIOT,Ell-i/RIOT,jbeyerstedt/RIOT-OTA-update,kbumsik/RIOT,gebart/RIOT,OlegHahm/RIOT,A-Paul/RIOT,jremmert-phytec-iot/RIOT,neumodisch/RIOT,dkm/RIOT,asanka-code/RIOT,attdona/RIOT,neumodisch/RIOT,brettswann/RIOT,beurdouche/RIOT,rajma996/RIOT,dailab/RIOT,altairpearl/RIOT,gebart/RIOT,altairpearl/RIOT,smlng/RIOT,basilfx/RIOT,roberthartung/RIOT,rakendrathapa/RIOT,backenklee/RIOT,miri64/RIOT,josephnoir/RIOT,dkm/RIOT,biboc/RIOT,miri64/RIOT,kbumsik/RIOT,mtausig/RIOT,josephnoir/RIOT,toonst/RIOT,miri64/RIOT,Ell-i/RIOT,beurdouche/RIOT,hamilton-mote/RIOT-OS,shady33/RIOT,biboc/RIOT,foss-for-synopsys-dwc-arc-processors/RIOT,d00616/RIOT,smlng/RIOT,smlng/RIOT,BytesGalore/RIOT,aeneby/RIOT,toonst/RIOT,jbeyerstedt/RIOT-OTA-update,basilfx/RIOT,FrancescoErmini/RIOT,katezilla/RIOT,kbumsik/RIOT,d00616/RIOT,x3ro/RIOT,katezilla/RIOT,jremmert-phytec-iot/RIOT,attdona/RIOT,brettswann/RIOT,Yonezawa-T2/RIOT,x3ro/RIOT,OTAkeys/RIOT,TobiasFredersdorf/RIOT,avmelnikoff/RIOT,biboc/RIOT,A-Paul/RIOT,d00616/RIOT,immesys/RiSyn,altairpearl/RIOT,jfischer-phytec-iot/RIOT,adjih/RIOT,kYc0o/RIOT,rakendrathapa/RIOT,rfuentess/RIOT,neumodisch/RIOT,rousselk/RIOT,neiljay/RIOT,rfuentess/RIOT,neumodisch/RIOT,mfrey/RIOT,authmillenon/RIOT,kb2ma/RIOT,basilfx/RIOT,mfrey/RIOT,ks156/RIOT,thomaseichinger/RIOT,brettswann/RIOT,syin2/RIOT,jfischer-phytec-iot/RIOT,jfischer-phytec-iot/RIOT,Yonezawa-T2/RIOT,MohmadAyman/RIOT,beurdouche/RIOT,jbeyerstedt/RIOT-OTA-update,zhuoshuguo/RIOT,jremmert-phytec-iot/RIOT,adrianghc/RIOT,syin2/RIOT,gautric/RIOT,mfrey/RIOT,biboc/RIOT,Josar/RIOT,mfrey/RIOT,kaleb-himes/RIOT,Josar/RIOT,LudwigOrtmann/RIOT,backenklee/RIOT,asanka-code/RIOT,zhuoshuguo/RIOT,jbeyerstedt/RIOT-OTA-update,yogo1212/RIOT,kYc0o/RIOT,RIOT-OS/RIOT,kerneltask/RIOT,josephnoir/RIOT,malosek/RIOT,kerneltask/RIOT,tfar/RIOT,OlegHahm/RIOT,plushvoxel/RIOT,adrianghc/RIOT,kaleb-himes/RIOT,thomaseichinger/RIOT,Yonezawa-T2/RIOT,BytesGalore/RIOT,brettswann/RIOT,LudwigKnuepfer/RIOT,RIOT-OS/RIOT,cladmi/RIOT,rakendrathapa/RIOT,RIOT-OS/RIOT,ks156/RIOT,smlng/RIOT,Josar/RIOT,kaleb-himes/RIOT,BytesGalore/RIOT,gautric/RIOT,A-Paul/RIOT,authmillenon/RIOT,OTAkeys/RIOT,mfrey/RIOT,kb2ma/RIOT,MohmadAyman/RIOT,authmillenon/RIOT,wentaoshang/RIOT,katezilla/RIOT,dailab/RIOT,syin2/RIOT,kaspar030/RIOT,OTAkeys/RIOT,OlegHahm/RIOT,shady33/RIOT,OTAkeys/RIOT,zhuoshuguo/RIOT,lazytech-org/RIOT,OlegHahm/RIOT,avmelnikoff/RIOT,josephnoir/RIOT,wentaoshang/RIOT,rfuentess/RIOT,kbumsik/RIOT,rousselk/RIOT,hamilton-mote/RIOT-OS,immesys/RiSyn,LudwigOrtmann/RIOT,rousselk/RIOT,kerneltask/RIOT,roberthartung/RIOT,miri64/RIOT,kaspar030/RIOT,alignan/RIOT,tfar/RIOT,malosek/RIOT,dailab/RIOT,authmillenon/RIOT,jasonatran/RIOT,altairpearl/RIOT,plushvoxel/RIOT,wentaoshang/RIOT,brettswann/RIOT,cladmi/RIOT,roberthartung/RIOT,rajma996/RIOT,neumodisch/RIOT,adjih/RIOT,mtausig/RIOT,kaspar030/RIOT,TobiasFredersdorf/RIOT,thomaseichinger/RIOT,ks156/RIOT,toonst/RIOT,BytesGalore/RIOT,kb2ma/RIOT,foss-for-synopsys-dwc-arc-processors/RIOT,avmelnikoff/RIOT,Hyungsin/RIOT-OS,hamilton-mote/RIOT-OS,jfischer-phytec-iot/RIOT,plushvoxel/RIOT,jfischer-phytec-iot/RIOT,neiljay/RIOT,shady33/RIOT,rousselk/RIOT,yogo1212/RIOT,Hyungsin/RIOT-OS,Yonezawa-T2/RIOT,dailab/RIOT,jbeyerstedt/RIOT-OTA-update,kaspar030/RIOT,ant9000/RIOT,rakendrathapa/RIOT,malosek/RIOT,gebart/RIOT,jasonatran/RIOT,kb2ma/RIOT,foss-for-synopsys-dwc-arc-processors/RIOT