AA: ramips: fix ASUS WL-330N3G MAC address

AA: ramips: fix ASUS WL-330N3G MAC address

Backport of r34877.

The ASUS WL-330N and WL-330N3G has the MAC address stored at
offset 4, not 40. This is verified by reading original ASUS
firmware GPL_WL-330N3G_source.1028/user/rc/common_ex.c and
GPL_WL-330N_source.1021/user/rc/common_ex.c.

Tested on WL-330N3G, it now gets the same MAC as is printed on
the label on the router.

Signed-off-by: Jan Kardell <jan.kardell@arkub.com>
Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
git-svn-id: svn://svn.openwrt.org/openwrt/branches/attitude_adjustment@34879 3c298f89-4303-0410-b956-a3cf2f4a3e73