net/mlx4_en: Fix traffic loss under promiscuous mode

When port is stopped and flow steering mode is not device managed: promisc QP
rule wasn't removed from MCG table.
Added code to remove it in all flow steering modes.
In addition, promsic rule removal should be in stop port and not in start
port - moved it accordingly.

Signed-off-by: Aviad Yehezkel <aviadye@mellanox.com>
Signed-off-by: Eugenia Emantayev <eugenia@mellanox.com>
Signed-off-by: Hadar Hen Zion <hadarh@mellanox.com>
Signed-off-by: Amir Vadai <amirv@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>