board/nucleo32: fix Arduino pin mapping
board/nucleo32: fix Arduino pin mapping

On Nucleo-32 boards with STM32 MCUs that do not have the GPIO port F, the Arduino pins D7 and D8 are not connected to PF0 and PF1 but to PC14 and PC15. This is also the case for the Nucleo-L412KB.
OTAkeys/RIOT,RIOT-OS/RIOT,OlegHahm/RIOT,authmillenon/RIOT,kYc0o/RIOT,miri64/RIOT,authmillenon/RIOT,RIOT-OS/RIOT,authmillenon/RIOT,kYc0o/RIOT,OTAkeys/RIOT,miri64/RIOT,kYc0o/RIOT,kaspar030/RIOT,OTAkeys/RIOT,RIOT-OS/RIOT,OTAkeys/RIOT,ant9000/RIOT,jasonatran/RIOT,miri64/RIOT,ant9000/RIOT,jasonatran/RIOT,OlegHahm/RIOT,jasonatran/RIOT,kaspar030/RIOT,RIOT-OS/RIOT,kaspar030/RIOT,ant9000/RIOT,kaspar030/RIOT,ant9000/RIOT,jasonatran/RIOT,kYc0o/RIOT,OlegHahm/RIOT,authmillenon/RIOT,RIOT-OS/RIOT,OTAkeys/RIOT,kYc0o/RIOT,OlegHahm/RIOT,miri64/RIOT,jasonatran/RIOT,authmillenon/RIOT,authmillenon/RIOT,ant9000/RIOT,kaspar030/RIOT,OlegHahm/RIOT,miri64/RIOT