stmhal: Use polling, not DMA, for 1 byte SPI transfers.
stmhal: Use polling, not DMA, for 1 byte SPI transfers.

There is an issue sending 1 byte on the SPI bus using DMA, but it only
occurs when the transmit is done for the first time after initialising
the SPI and DMA peripherals.  All other cases (sending 2 or more bytes,
doing send_recv, doing recv first) work okay.  We sidestep this issue by
using polling (not DMA) for all 1 byte transfers.  This is fine because
a 1 byte transfer can't be interrupted and doesn't need the benefits of
DMA (and using polling for this case is more efficient).

Resolves #1456.

dinau/micropython,dhylands/micropython,micropython/micropython-esp32,HenrikSolver/micropython,ganshun666/micropython,oopy/micropython,neilh10/micropython,Peetz0r/micropython-esp32,jmarcelino/pycom-micropython,pramasoul/micropython,rubencabrera/micropython,torwag/micropython,emfcamp/micropython,galenhz/micropython,blmorris/micropython,matthewelse/micropython,ericsnowcurrently/micropython,MrSurly/micropython-esp32,lowRISC/micropython,deshipu/micropython,omtinez/micropython,selste/micropython,emfcamp/micropython,Peetz0r/micropython-esp32,SHA2017-badge/micropython-esp32,feilongfl/micropython,hiway/micropython,jmarcelino/pycom-micropython,torwag/micropython,oopy/micropython,vitiral/micropython,jmarcelino/pycom-micropython,dinau/micropython,puuu/micropython,pozetroninc/micropython,vitiral/micropython,rubencabrera/micropython,redbear/micropython,xhat/micropython,alex-march/micropython,praemdonck/micropython,henriknelson/micropython,SHA2017-badge/micropython-esp32,cloudformdesign/micropython,infinnovation/micropython,pramasoul/micropython,redbear/micropython,infinnovation/micropython,mhoffma/micropython,emfcamp/micropython,SHA2017-badge/micropython-esp32,neilh10/micropython,matthewelse/micropython,blmorris/micropython,SHA2017-badge/micropython-esp32,infinnovation/micropython,blazewicz/micropython,ChuckM/micropython,omtinez/micropython,misterdanb/micropython,ericsnowcurrently/micropython,hosaka/micropython,dmazzella/micropython,ruffy91/micropython,swegener/micropython,TDAbboud/micropython,danicampora/micropython,supergis/micropython,ruffy91/micropython,ernesto-g/micropython,omtinez/micropython,torwag/micropython,hosaka/micropython,kerneltask/micropython,Peetz0r/micropython-esp32,vriera/micropython,pozetroninc/micropython,ruffy91/micropython,turbinenreiter/micropython,EcmaXp/micropython,chrisdearman/micropython,xhat/micropython,hosaka/micropython,tuc-osg/micropython,mianos/micropython,HenrikSolver/micropython,alex-robbins/micropython,henriknelson/micropython,mhoffma/micropython,xuxiaoxin/micropython,mhoffma/micropython,mpalomer/micropython,danicampora/micropython,praemdonck/micropython,matthewelse/micropython,ChuckM/micropython,martinribelotta/micropython,hiway/micropython,dmazzella/micropython,cloudformdesign/micropython,adafruit/circuitpython,HenrikSolver/micropython,ericsnowcurrently/micropython,drrk/micropython,praemdonck/micropython,swegener/micropython,neilh10/micropython,TDAbboud/micropython,dxxb/micropython,micropython/micropython-esp32,alex-march/micropython,alex-march/micropython,PappaPeppar/micropython,turbinenreiter/micropython,trezor/micropython,infinnovation/micropython,kerneltask/micropython,tobbad/micropython,mpalomer/micropython,noahwilliamsson/micropython,galenhz/micropython,bvernoux/micropython,swegener/micropython,lowRISC/micropython,pozetroninc/micropython,blmorris/micropython,AriZuu/micropython,martinribelotta/micropython,tuc-osg/micropython,swegener/micropython,rubencabrera/micropython,feilongfl/micropython,xuxiaoxin/micropython,toolmacher/micropython,Timmenem/micropython,ganshun666/micropython,pozetroninc/micropython,emfcamp/micropython,ChuckM/micropython,hiway/micropython,dxxb/micropython,dhylands/micropython,feilongfl/micropython,dxxb/micropython,dmazzella/micropython,swegener/micropython,dinau/micropython,cloudformdesign/micropython,drrk/micropython,adafruit/micropython,selste/micropython,lowRISC/micropython,orionrobots/micropython,feilongfl/micropython,tobbad/micropython,TDAbboud/micropython,toolmacher/micropython,rubencabrera/micropython,dinau/micropython,chrisdearman/micropython,bvernoux/micropython,drrk/micropython,AriZuu/micropython,lowRISC/micropython,hiway/micropython,pozetroninc/micropython,adamkh/micropython,mhoffma/micropython,noahwilliamsson/micropython,tralamazza/micropython,adafruit/circuitpython,trezor/micropython,xhat/micropython,omtinez/micropython,xuxiaoxin/micropython,lowRISC/micropython,misterdanb/micropython,kerneltask/micropython,toolmacher/micropython,neilh10/micropython,deshipu/micropython,torwag/micropython,blmorris/micropython,mianos/micropython,alex-march/micropython,dinau/micropython,martinribelotta/micropython,dxxb/micropython,chrisdearman/micropython,ernesto-g/micropython,bvernoux/micropython,MrSurly/micropython-esp32,micropython/micropython-esp32,Peetz0r/micropython-esp32,pfalcon/micropython,blazewicz/micropython,ryannathans/micropython,Timmenem/micropython,deshipu/micropython,xuxiaoxin/micropython,selste/micropython,tuc-osg/micropython,ernesto-g/micropython,PappaPeppar/micropython,adafruit/micropython,noahwilliamsson/micropython,cwyark/micropython,tuc-osg/micropython,vriera/micropython,martinribelotta/micropython,cwyark/micropython,supergis/micropython,Timmenem/micropython,tobbad/micropython,blmorris/micropython,tralamazza/micropython,tobbad/micropython,trezor/micropython,micropython/micropython-esp32,PappaPeppar/micropython,ChuckM/micropython,noahwilliamsson/micropython,turbinenreiter/micropython,adafruit/micropython,infinnovation/micropython,danicampora/micropython,pramasoul/micropython,adamkh/micropython,HenrikSolver/micropython,ernesto-g/micropython,alex-march/micropython,Timmenem/micropython,blazewicz/micropython,Peetz0r/micropython-esp32,toolmacher/micropython,tuc-osg/micropython,mpalomer/micropython,xuxiaoxin/micropython,MrSurly/micropython,puuu/micropython,EcmaXp/micropython,neilh10/micropython,matthewelse/micropython,selste/micropython,cloudformdesign/micropython,pramasoul/micropython,adafruit/circuitpython,praemdonck/micropython,noahwilliamsson/micropython,hiway/micropython,galenhz/micropython,alex-robbins/micropython,pfalcon/micropython,kerneltask/micropython,hosaka/micropython,MrSurly/micropython-esp32,mpalomer/micropython,jlillest/micropython,jlillest/micropython,toolmacher/micropython,MrSurly/micropython,orionrobots/micropython,ganshun666/micropython,vitiral/micropython,blazewicz/micropython,adamkh/micropython,bvernoux/micropython,pfalcon/micropython,dhylands/micropython,chrisdearman/micropython,adafruit/circuitpython,danicampora/micropython,misterdanb/micropython,rubencabrera/micropython,adamkh/micropython,henriknelson/micropython,adafruit/circuitpython,MrSurly/micropython,henriknelson/micropython,selste/micropython,mianos/micropython,vriera/micropython,ryannathans/micropython,redbear/micropython,turbinenreiter/micropython,SHA2017-badge/micropython-esp32,supergis/micropython,misterdanb/micropython,alex-robbins/micropython,oopy/micropython,emfcamp/micropython,drrk/micropython,adafruit/circuitpython,ruffy91/micropython,hosaka/micropython,EcmaXp/micropython,TDAbboud/micropython,puuu/micropython,xhat/micropython,henriknelson/micropython,puuu/micropython,galenhz/micropython,HenrikSolver/micropython,matthewelse/micropython,ruffy91/micropython,alex-robbins/micropython,vriera/micropython,tobbad/micropython,dhylands/micropython,pramasoul/micropython,martinribelotta/micropython,mianos/micropython,ericsnowcurrently/micropython,oopy/micropython,EcmaXp/micropython,mhoffma/micropython,ernesto-g/micropython,jmarcelino/pycom-micropython,cwyark/micropython,chrisdearman/micropython,MrSurly/micropython-esp32,omtinez/micropython,ryannathans/micropython,orionrobots/micropython,puuu/micropython,jlillest/micropython,jmarcelino/pycom-micropython,ryannathans/micropython,galenhz/micropython,micropython/micropython-esp32,PappaPeppar/micropython,trezor/micropython,trezor/micropython,adafruit/micropython,ryannathans/micropython,mianos/micropython,redbear/micropython,bvernoux/micropython,dxxb/micropython,vriera/micropython,tralamazza/micropython,adamkh/micropython,danicampora/micropython,pfalcon/micropython,Timmenem/micropython,turbinenreiter/micropython,MrSurly/micropython-esp32,praemdonck/micropython,redbear/micropython,deshipu/micropython,misterdanb/micropython,supergis/micropython,MrSurly/micropython,AriZuu/micropython,alex-robbins/micropython,ganshun666/micropython,drrk/micropython,AriZuu/micropython,MrSurly/micropython,deshipu/micropython,oopy/micropython,mpalomer/micropython,kerneltask/micropython,matthewelse/micropython,supergis/micropython,ericsnowcurrently/micropython,TDAbboud/micropython,PappaPeppar/micropython,dmazzella/micropython,torwag/micropython,cwyark/micropython,ganshun666/micropython,adafruit/micropython,cloudformdesign/micropython,orionrobots/micropython,ChuckM/micropython,dhylands/micropython,xhat/micropython,cwyark/micropython,orionrobots/micropython,blazewicz/micropython,jlillest/micropython,vitiral/micropython,pfalcon/micropython,vitiral/micropython,feilongfl/micropython,EcmaXp/micropython,tralamazza/micropython,AriZuu/micropython,jlillest/micropython