net: marvell: prestera: implement br_port_locked flag offloading

Both <port> br_port_locked and <lag> interfaces's flag
offloading is supported. No new ABI is being added,
rather existing (port_param_set) API call gets extended.

Signed-off-by: Oleksandr Mazur <oleksandr.mazur@plvision.eu>

V2:
  add missing receipents (linux-kernel, netdev)
Signed-off-by: David S. Miller <davem@davemloft.net>