mlxsw: core_acl_flex_actions: Add L4_PORT_ACTION

Add fields related to L4_PORT_ACTION, which is used for changing of TCP and
UDP port numbers.

Signed-off-by: Petr Machata <petrm@mellanox.com>
Reviewed-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>