sys/od/kconfig: add od_string
sys/od/kconfig: add od_string

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