stm32/boards/NUCLEO_L073RZ: Skip board-pin names for CPU only pins.
stm32/boards/NUCLEO_L073RZ: Skip board-pin names for CPU only pins.

This board doesn't have much flash and removing these unneeded names saves
about 900 bytes of code size.

pfalcon/micropython,pfalcon/micropython,pfalcon/micropython,pfalcon/micropython,pfalcon/micropython