cpu/efm32/efr32mg1p: Add Kconfig symbols
cpu/efm32/efr32mg1p: Add Kconfig symbols

authmillenon/RIOT,ant9000/RIOT,ant9000/RIOT,OTAkeys/RIOT,authmillenon/RIOT,kYc0o/RIOT,RIOT-OS/RIOT,OlegHahm/RIOT,OTAkeys/RIOT,kYc0o/RIOT,authmillenon/RIOT,jasonatran/RIOT,authmillenon/RIOT,basilfx/RIOT,kaspar030/RIOT,RIOT-OS/RIOT,miri64/RIOT,kaspar030/RIOT,kYc0o/RIOT,RIOT-OS/RIOT,jasonatran/RIOT,miri64/RIOT,kaspar030/RIOT,OlegHahm/RIOT,authmillenon/RIOT,basilfx/RIOT,basilfx/RIOT,authmillenon/RIOT,basilfx/RIOT,OTAkeys/RIOT,RIOT-OS/RIOT,OTAkeys/RIOT,OlegHahm/RIOT,basilfx/RIOT,jasonatran/RIOT,kYc0o/RIOT,kaspar030/RIOT,kaspar030/RIOT,jasonatran/RIOT,OlegHahm/RIOT,ant9000/RIOT,miri64/RIOT,miri64/RIOT,RIOT-OS/RIOT,kYc0o/RIOT,miri64/RIOT,ant9000/RIOT,OTAkeys/RIOT,jasonatran/RIOT,OlegHahm/RIOT,ant9000/RIOT