stm32/boards/stm32f429_af.csv: Fix typos in UART defs Tx->TX and Rx->RX.
stm32/boards/stm32f429_af.csv: Fix typos in UART defs Tx->TX and Rx->RX.

Fixes issue #4445.

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