net/mlx4: Query device for QoS per VF support

Checks in QUERY_DEV_CAP if the granular QoS per VF feature is
supported by the device. Disabled for guests.

Signed-off-by: Ido Shamay <idos@mellanox.com>
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>