net/mlx4_core: Support mirroring VF DMFS rules on both ports

Under HA mode, steering rules set by VFs should be mirrored on both
ports of the device so packets will be accepted no matter on which
port they arrived.

Since getting into HA mode is done dynamically when the user bonds mlx4
Ethernet netdevs, we keep hold of the VF DMFS rule mbox with the port
value flipped (1->2,2->1) and execute the mirroring when getting into
HA mode. Later, when going out of HA mode, we unset the mirrored rules.
In that context note that mirrored rules cannot be removed explicitly.

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