net: lan966x: Extend switchdev bridge flags

Currently allow a port to be part or not of the multicast flooding mask.
By implementing the switchdev calls SWITCHDEV_ATTR_ID_PORT_BRIDGE_FLAGS
and SWITCHDEV_ATTR_ID_PORT_PRE_BRIDGE_FLAGS.

Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>
Signed-off-by: David S. Miller <davem@davemloft.net>