ar71xx: UBNT Secondary MAC address duplicate fix

ar71xx: UBNT Secondary MAC address duplicate fix

There is Secondary MAC address duplicate problem with some UBNT
RouterStation and RouterStation Pro HW batches as Primary MAC addresses
are not increased by 2 per device in board data. Fix is to use 'Locally
Administrated bit' for Secondary MAC address instead of increasing
Primary MAC addresses by 1 which could overlap with other device
Primary MAC address.

Signed-off-by: Kestutis Barkauskas<keba@devint.net>
git-svn-id: svn://svn.openwrt.org/openwrt/trunk@24643 3c298f89-4303-0410-b956-a3cf2f4a3e73