net/mlx5: Support internal port as decap route device

When performing route device lookup for decap action, support
the case of ovs internal port as the lookup result.

In such case, an internal port struct is mapped and attached
to the flow attributes so that the source port matching of the
rule will match on the internal port's metadata value.

Signed-off-by: Ariel Levkovich <lariel@nvidia.com>
Reviewed-by: Vlad Buslov <vladbu@nvidia.com>
Reviewed-by: Roi Dayan <roid@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>