mvebu: Fix mac addresses for GL.iNet GL-MV1000

mvebu: Fix mac addresses for GL.iNet GL-MV1000

The original GL.iNet firmware has two different mac addresses in the
factory/art partition. The first one is for the WAN interface only and the
second one is for both lan0 and lan1.

But the original submission for OpenWrt didn't initialize the mac
addresses of the LAN ports for the DSA device at all. The ethernet mac
address was then used for all DSA ports.

Fixes: 050c24f05c85 ("mvebu: add support for GL.iNet GL-MV1000")
Signed-off-by: Sven Eckelmann <sven@narfation.org>
(cherry picked from commit c20ac84803242e5a6451184009dabc36ba83b96e)