net/mlx4_core: Add UPDATE_QP SRIOV wrapper support

This patch adds UPDATE_QP SRIOV wrapper support.

The mechanism is a general one, but currently only source MAC
index changes are allowed for VFs.

Signed-off-by: Matan Barak <matanb@mellanox.com>
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>