openwrt: tp-link region code for wr841-v11

Fixes #16

Signed-off-by: Tim Niemeyer <tim@tn-x.org>
Reviewed-by: Jan Kraus <mayosemmel@gmail.com>
Tested-by: Tim Niemeyer <tim@tn-x.org>
Reviewed-by: Tobias Klaus <tk+ff@meskal.net>