Add support for configuring per port unknown flooding by accepting both
BR_FLOOD and BR_MCAST_FLOOD as offloadable bridge port flags.

The DPAA2 switch does not support at the moment configuration of unknown
multicast flooding independently of unknown unicast flooding, therefore
check that both BR_FLOOD and BR_MCAST_FLOOD have the same state.
Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>