ar71xx: add kernel support for the TL-MR3220 v2

Based on the following patch:
http://patchwork.openwrt.org/patch/3043/



[juhosg:
 - remove custom LED and button arrays
 - use separate machine specific patch
 - update Kconfig]

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

SVN-Revision: 34779