boards: nucleo_f429zi: Fix typo in code comments
boards: nucleo_f429zi: Fix typo in code comments

Fix minor typo in code comments of pinmux.c

Signed-off-by: Christian Taedcke <1d7d3458c4d94e1013a9872dbd5fe0865ba6a124@taedcke.com>

Vudentz/zephyr,finikorg/zephyr,punitvara/zephyr,punitvara/zephyr,ldts/zephyr,ldts/zephyr,GiulianoFranchetto/zephyr,punitvara/zephyr,GiulianoFranchetto/zephyr,galak/zephyr,explora26/zephyr,GiulianoFranchetto/zephyr,Vudentz/zephyr,explora26/zephyr,galak/zephyr,finikorg/zephyr,nashif/zephyr,explora26/zephyr,Vudentz/zephyr,finikorg/zephyr,punitvara/zephyr,Vudentz/zephyr,ldts/zephyr,zephyrproject-rtos/zephyr,Vudentz/zephyr,zephyrproject-rtos/zephyr,punitvara/zephyr,ldts/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,finikorg/zephyr,GiulianoFranchetto/zephyr,nashif/zephyr,zephyrproject-rtos/zephyr,nashif/zephyr,finikorg/zephyr,ldts/zephyr,galak/zephyr,explora26/zephyr,Vudentz/zephyr,GiulianoFranchetto/zephyr,galak/zephyr,nashif/zephyr,zephyrproject-rtos/zephyr,nashif/zephyr,explora26/zephyr