cpu/atmega_common: Add Kconfig symbols
cpu/atmega_common: Add Kconfig symbols

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