ar71xx: add kernel support for the Netgear WNR612 v2 board

Netgear WNR612 v2:
 - cpu Atheros AR7240 (Python) @400MHz
 - flash 4MB
 - ram 32MB
 - ethernet 10/100: 1xwan + 2xlan (only two)
 - radio AR9285

[juhosg: use a separate kernel patch]

Signed-off-by: Cezary Jackiewicz <cezary.jackiewicz@gmail.com>
Patchwork: http://patchwork.openwrt.org/patch/3876/


Signed-off-by: Gabor Juhos <juhosg@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@37575 3c298f89-4303-0410-b956-a3cf2f4a3e73