net: bridge: Add support for offloading of locked port flag

Various switchcores support setting ports in locked mode, so that
clients behind locked ports cannot send traffic through the port
unless a fdb entry is added with the clients MAC address.

Signed-off-by: Hans Schultz <schultz.hans+netdev@gmail.com>
Acked-by: Nikolay Aleksandrov <nikolay@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>