nrf/mphalport: Use wfi to save power while waiting at the UART REPL.
nrf/mphalport: Use wfi to save power while waiting at the UART REPL.

bvernoux/micropython,pfalcon/micropython,adafruit/circuitpython,pfalcon/micropython,adafruit/circuitpython,tobbad/micropython,adafruit/circuitpython,henriknelson/micropython,tobbad/micropython,trezor/micropython,kerneltask/micropython,MrSurly/micropython,trezor/micropython,pozetroninc/micropython,bvernoux/micropython,kerneltask/micropython,pramasoul/micropython,pramasoul/micropython,tobbad/micropython,adafruit/circuitpython,trezor/micropython,kerneltask/micropython,pramasoul/micropython,adafruit/circuitpython,MrSurly/micropython,pozetroninc/micropython,kerneltask/micropython,pfalcon/micropython,henriknelson/micropython,kerneltask/micropython,pfalcon/micropython,pozetroninc/micropython,MrSurly/micropython,adafruit/circuitpython,trezor/micropython,trezor/micropython,tobbad/micropython,pramasoul/micropython,henriknelson/micropython,pfalcon/micropython,henriknelson/micropython,selste/micropython,selste/micropython,selste/micropython,bvernoux/micropython,bvernoux/micropython,pramasoul/micropython,henriknelson/micropython,pozetroninc/micropython,MrSurly/micropython,MrSurly/micropython,tobbad/micropython,pozetroninc/micropython,selste/micropython,selste/micropython,bvernoux/micropython