nrf: Use --gc-sections to reduce code size
nrf: Use --gc-sections to reduce code size

This saves about 6-7kB.

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