IB/mlx4: Use the VF base-port when demuxing mad from wire

Under HA mode, it's possible that the VF registered its GID
(and expects to get mads through the PV scheme) on a port which is
different from the one this mad arrived on, due to HA fail over.

Therefore, if the gid is not matched on the port that the packet arrived
on, check for a match on the other port if HA mode is active -- and if a
match is found on the other port, continue processing the mad using that
other port.

Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Reviewed-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: David S. Miller <davem@davemloft.net>