net/mlx5: add port ID pattern item to switch flow rules

net/mlx5: add port ID pattern item to switch flow rules

This enables flow rules to match traffic coming from a different DPDK port
ID associated with the device (PORT_ID pattern item), mainly for the
convenience of applications that want to deal with a single port ID for all
flow rules associated with some physical device.

Testpmd example:

- Creating a flow rule on port ID 1 to consume all traffic from port ID 0
  and direct it to port ID 2:

  flow create 1 ingress transfer pattern port_id id is 0 / end actions
     port_id id 2 / end

Signed-off-by: Adrien Mazarguil <adrien.mazarguil@6wind.com>
Acked-by: Nelio Laranjeiro <nelio.laranjeiro@6wind.com>
Acked-by: Yongseok Koh <yskoh@mellanox.com>