net: calxedaxgmac: add uc and mc filter addresses in promiscuous mode

Even in promiscuous mode, we need to add filter addresses for correct
operation. This fixes silent failures when using a bridge and adding
addresses using the "bridge fdb add" command.

Signed-off-by: Rob Herring <rob.herring@calxeda.com>
Signed-off-by: David S. Miller <davem@davemloft.net>