stm32/extint: Simplify bitband support config for different MCUs.
stm32/extint: Simplify bitband support config for different MCUs.

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