pkg/gecko_sdk: Disable -Wcast-align
pkg/gecko_sdk: Disable -Wcast-align

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