boards/slwstk6220a: Add Kconfig symbols
boards/slwstk6220a: Add Kconfig symbols

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