net/mlx5: Add support for COPY steering action

Add COPY type to modify_header action. IPsec feature is the first
feature that needs COPY steering action.

Signed-off-by: Huy Nguyen <huyn@mellanox.com>
Signed-off-by: Raed Salem <raeds@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Acked-by: Leon Romanovsky <leonro@mellanox.com>