net/mlx5: Disable VF tunnel TX offload if ignore_flow_level isn't supported

VF tunnel TX traffic offload is adding flow which forward to flow
tables with lower level, which isn't support on all FW versions
and may cause firmware to fail with syndrome.

Fixed by enabling VF tunnel TX offload only if flow table capability
ignore_flow_level is enabled.

Fixes: 10742efc

 ("net/mlx5e: VF tunnel TX traffic offloading")
Signed-off-by: Maor Dickman <maord@nvidia.com>
Reviewed-by: Vlad Buslov <vladbu@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>