cc3200/mods/pybi2c: Make readfnom_mem_into/writeto_mem return None.
cc3200/mods/pybi2c: Make readfnom_mem_into/writeto_mem return None.

This aligns the I2C class to match the standard machine.I2C API.

Note that this is a (small) breaking change to the existing cc3200 API.
The original API just returned the size of the input buffer so there's no
information lost by this change.  To update scripts users should just use
the size of the buffer passed to these functions to get the number of bytes
that are read/written.

kerneltask/micropython,AriZuu/micropython,pozetroninc/micropython,cwyark/micropython,MrSurly/micropython,toolmacher/micropython,MrSurly/micropython,SHA2017-badge/micropython-esp32,MrSurly/micropython,oopy/micropython,adafruit/micropython,infinnovation/micropython,hiway/micropython,adafruit/circuitpython,bvernoux/micropython,kerneltask/micropython,lowRISC/micropython,cwyark/micropython,alex-robbins/micropython,Timmenem/micropython,adafruit/circuitpython,HenrikSolver/micropython,pozetroninc/micropython,MrSurly/micropython-esp32,puuu/micropython,pramasoul/micropython,adafruit/circuitpython,selste/micropython,torwag/micropython,tralamazza/micropython,torwag/micropython,cwyark/micropython,oopy/micropython,chrisdearman/micropython,lowRISC/micropython,blazewicz/micropython,pozetroninc/micropython,blazewicz/micropython,deshipu/micropython,selste/micropython,micropython/micropython-esp32,alex-robbins/micropython,PappaPeppar/micropython,bvernoux/micropython,lowRISC/micropython,adafruit/micropython,pfalcon/micropython,kerneltask/micropython,puuu/micropython,oopy/micropython,HenrikSolver/micropython,tobbad/micropython,SHA2017-badge/micropython-esp32,dmazzella/micropython,swegener/micropython,SHA2017-badge/micropython-esp32,pfalcon/micropython,tobbad/micropython,swegener/micropython,SHA2017-badge/micropython-esp32,PappaPeppar/micropython,dmazzella/micropython,toolmacher/micropython,trezor/micropython,AriZuu/micropython,MrSurly/micropython,infinnovation/micropython,Timmenem/micropython,puuu/micropython,blazewicz/micropython,lowRISC/micropython,PappaPeppar/micropython,swegener/micropython,TDAbboud/micropython,AriZuu/micropython,tralamazza/micropython,pfalcon/micropython,bvernoux/micropython,chrisdearman/micropython,selste/micropython,pozetroninc/micropython,alex-robbins/micropython,blazewicz/micropython,SHA2017-badge/micropython-esp32,TDAbboud/micropython,adafruit/circuitpython,MrSurly/micropython-esp32,toolmacher/micropython,micropython/micropython-esp32,oopy/micropython,selste/micropython,adafruit/circuitpython,PappaPeppar/micropython,adafruit/micropython,blazewicz/micropython,trezor/micropython,chrisdearman/micropython,torwag/micropython,deshipu/micropython,oopy/micropython,tralamazza/micropython,trezor/micropython,Timmenem/micropython,tralamazza/micropython,MrSurly/micropython-esp32,pramasoul/micropython,selste/micropython,toolmacher/micropython,chrisdearman/micropython,trezor/micropython,swegener/micropython,infinnovation/micropython,MrSurly/micropython-esp32,ryannathans/micropython,adafruit/circuitpython,trezor/micropython,MrSurly/micropython,alex-robbins/micropython,henriknelson/micropython,toolmacher/micropython,HenrikSolver/micropython,pramasoul/micropython,bvernoux/micropython,puuu/micropython,torwag/micropython,pfalcon/micropython,AriZuu/micropython,tobbad/micropython,infinnovation/micropython,HenrikSolver/micropython,lowRISC/micropython,ryannathans/micropython,puuu/micropython,TDAbboud/micropython,alex-robbins/micropython,HenrikSolver/micropython,ryannathans/micropython,hiway/micropython,Timmenem/micropython,hiway/micropython,micropython/micropython-esp32,deshipu/micropython,dmazzella/micropython,TDAbboud/micropython,henriknelson/micropython,PappaPeppar/micropython,hiway/micropython,MrSurly/micropython-esp32,micropython/micropython-esp32,bvernoux/micropython,pramasoul/micropython,ryannathans/micropython,micropython/micropython-esp32,cwyark/micropython,cwyark/micropython,tobbad/micropython,ryannathans/micropython,infinnovation/micropython,pramasoul/micropython,AriZuu/micropython,hiway/micropython,dmazzella/micropython,deshipu/micropython,adafruit/micropython,adafruit/micropython,kerneltask/micropython,kerneltask/micropython,henriknelson/micropython,chrisdearman/micropython,henriknelson/micropython,tobbad/micropython,torwag/micropython,Timmenem/micropython,deshipu/micropython,henriknelson/micropython,TDAbboud/micropython,pozetroninc/micropython,pfalcon/micropython,swegener/micropython