net/mlx5: rewrite MAC address by E-Switch

net/mlx5: rewrite MAC address by E-Switch

Offload following modify MAC address actions to E-Switch
via TC-Flower driver

- RTE_FLOW_ACTION_TYPE_SET_MAC_SRC
- RTE_FLOW_ACTION_TYPE_SET_MAC_DST

The corresponding rte_flow_item_eth must be present in
rte_flow pattern

Only support modify outer layer MAC address

The example testpmd command is:

    flow create 0 transfer ingress
         pattern eth / ipv4 / udp dst is 7000 / end
         actions set_mac_dst mac_addr dd:00:aa:11:bb:33 /
         set_mac_src mac_addr bb:00:cc:11:aa:22 /
	 port_id id 1 / end

Signed-off-by: Xiaoyu Min <jackmin@mellanox.com>
Acked-by: Yongseok Koh <yskoh@mellanox.com>