brcm47xx: board detection WNDR3400v2

WNDR3400v2 is based on BCM53xx . Image that is created breaks the router somehow therefore "#".

CFE and NVRAM contain different vars - example:
CFE line original: Device eth0:  hwaddr 74-44-01-37-C6-69, ipaddr 192.168.1.1, mask 255.255.255.0
CFE after openwrt: Device eth0:  hwaddr 00-FF-FF-FF-FF-FF, ipaddr 192.168.1.1, mask 255.255.255.0

Logs were posted earlier on this mailing list: https://lists.openwrt.org/pipermail/openwrt-devel/2012-July/016174.html
Different logs with factory firmware are in the wiki: http://wiki.openwrt.org/toh/netgear/wndr3400#wndr3400v2
(and on wikidevi for example)

Signed off by: Dirk Neukirchen <dirkneukirchen@web.de>

SVN-Revision: 35790