IB/mlx5: Merge vports flow steering during LAG

This is done in two steps:
1) Issuing CREATE_VPORT_LAG in order to have Ethernet traffic from
both ports arriving on PF0 root flowtable, so we will be able to catch
all raw-eth traffic on PF0.
2) Creation of LAG demux flowtable in order to direct all non-raw-eth
traffic back to its source port, assuring that normal Ethernet
traffic "jumps" to the root flowtable of its RX port (non-LAG behavior).

Signed-off-by: Aviv Heller <avivh@mellanox.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Doug Ledford <dledford@redhat.com>