net/mlx4_core: Turn off device-managed FS bit in dev-cap wrapper if DMFS is not enabled

Older kernels detect DMFS (device-managed flow steering) from the HCA
device capability directly, regardless of whether the capability was
enabled in INIT_HCA, this is fixed by commit 7b8157be "mlx4_core: Adjustments
to Flow Steering activation logic for SR-IOV"

To protect against guests running kernels without this fix, the host driver
should turn off the DMFS capability bit in mlx4_QUERY_DEV_CAP_wrapper.

Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>