stm32/main: Fix auto creation of pyb.Flash on boot with kw-only args.
stm32/main: Fix auto creation of pyb.Flash on boot with kw-only args.

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