vdpa/mlx5: Return error on vlan ctrl commands if not supported

Check if VIRTIO_NET_F_CTRL_VLAN is negotiated and return error if
control VQ command is received.

Signed-off-by: Eli Cohen <elic@nvidia.com>
Message-Id: <20221114131759.57883-3-elic@nvidia.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Acked-by: Eugenio Pérez <eperezma@redhat.com>