net/mlx4_core: In SR-IOV mode host should add promisc QP to default entry only

In current situation host is adding the promiscuous QP to all steering
entries and the default entry as well. In this case when having PV
and SR-IOV on the same setup bridge will receive all traffic that is
targeted to the other VMs. This is bad.
Solution: In SR-IOV mode host can add promiscuous QP to default entry only.
The above problem and fix are relevant for B0 steering mode only.

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>