tests/periph_gpio_ll: use MCU instead of CPU_FAM for ESP32x SoC
tests/periph_gpio_ll: use MCU instead of CPU_FAM for ESP32x SoC

To be able to compile the test for different ESP32x variants without defining each ESP32x variant, MCU has to be used instead of CPU_FAM.
miri64/RIOT,kYc0o/RIOT,kaspar030/RIOT,miri64/RIOT,jasonatran/RIOT,miri64/RIOT,kaspar030/RIOT,kYc0o/RIOT,RIOT-OS/RIOT,miri64/RIOT,RIOT-OS/RIOT,jasonatran/RIOT,kaspar030/RIOT,RIOT-OS/RIOT,jasonatran/RIOT,ant9000/RIOT,kYc0o/RIOT,RIOT-OS/RIOT,ant9000/RIOT,jasonatran/RIOT,ant9000/RIOT,ant9000/RIOT,kYc0o/RIOT,miri64/RIOT,kaspar030/RIOT,kaspar030/RIOT,jasonatran/RIOT,ant9000/RIOT,RIOT-OS/RIOT,kYc0o/RIOT