net/mlx5: E-Switch, Use metadata matching for RoCE loopback rule

Use metadata matching for RoCE loopback rule if device is configured
to use metadata for source port matching.

Signed-off-by: Roi Dayan <roid@nvidia.com>
Reviewed-by: Maor Dickman <maord@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>