stm32/spi: Fix calculation of SPI clock source on H7 MCUs.
stm32/spi: Fix calculation of SPI clock source on H7 MCUs.

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