boards/avsextrem: Add Kconfig symbols
boards/avsextrem: Add Kconfig symbols

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