wlcore/wl18xx/wl12xx: allow up to 3 mac addresses

Allow 3 native mac addresses on 18xx. On 12xx allow 2 native mac
addresses and set the LAA bit to create a third mac address. This
enabled operation with a separate group interface.

Signed-off-by: Arik Nemtsov <arik@wizery.com>
Signed-off-by: Luciano Coelho <luca@coelho.fi>