net/mlx4_en: Do not disable vlan filter during promiscuous mode

Promiscous mode is only for MACs.
Should not disable/enable VLAN filter when entering/leaving promisuous mode.

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