AA: ar71xx: TP-LINK also has a family TL-WDR

Backport of r34577.

Signed-off-by: Cezary Jackiewicz <cezary.jackiewicz@gmail.com>
Signed-off-by: Gabor Juhos <juhosg@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/branches/attitude_adjustment@38012 3c298f89-4303-0410-b956-a3cf2f4a3e73