net/mlx5e: E-Switch, Remove flow_source check for metadata matching

There is no reason to check for flow_source cap to allow metadata
matching. When flow_source match is being used the flow_source cap
is being checked.

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