ar71xx: build images for the TP-LINK TL-WR743ND v2

AR9331 based, these same as 741v4

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@35449 3c298f89-4303-0410-b956-a3cf2f4a3e73