IB/mlx4: When no DMFS for IPoIB, don't allow NET_IF QPs

According to the firmware spec, FLOW_STEERING_IB_UC_QP_RANGE command is
supported only if dmfs_ipoib bit is set.

If it isn't set we want to ensure allocating NET_IF QPs fail. We do so
by filling out the allocation bitmap. By thus, the NET_IF QPs allocating
function won't find any free QP and will fail.

Fixes: c1c98501

 ('IB/mlx4: Add support for steerable IB UD QPs')
Signed-off-by: Eran Ben Elisha <eranbe@mellanox.com>
Signed-off-by: Daniel Jurgens <danielj@mellanox.com>
Reviewed-by: Mark Bloch <markb@mellanox.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Doug Ledford <dledford@redhat.com>