mlx4_core: Add QPN enforcement for flow steering rules set by VFs

Since VFs may be mapped to VMs which aren't trusted entities, flow
steering rules attached through the wrapper on behalf of VFs must be
checked to make sure that the specified QP number is assigned to that
VF.  Also, make sure to keep the QP busy till the end of the operation
from the resource tracker point of view.

Signed-off-by: Hadar Hen Zion <hadarh@mellanox.com>
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>