ar71xx: WNR1000v2: fix for random WLAN MAC

Fix for invalid/random WLAN MAC address in WNR1000v2. Permanent platform
MAC is calculated and assigned during system startup. WLAN MAC follows
wired Ethernet interface addresses. This is the same fix as for WNR2000v3
and WNR612v2.

Signed-off-by: Michal Cieslakiewicz <michal.cieslakiewicz@wp.pl>

SVN-Revision: 49051