switchdev: Make flood to CPU optional

In certain use cases it is not always desirable for the switch device to
flood traffic to CPU port. Instead, only certain packet types (e.g.
STP, LACP) should be trapped to it.
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/networking/switchdev.txt

@@ -278,8 +278,8 @@ Flooding L2 domain
 For a given L2 VLAN domain, the switch device should flood multicast/broadcast
 and unknown unicast packets to all ports in domain, if allowed by port's
 current STP state.  The switch driver, knowing which ports are within which
-vlan L2 domain, can program the switch device for flooding.  The packet should
-also be sent to the port netdev for processing by the bridge driver.  The
+vlan L2 domain, can program the switch device for flooding.  The packet may
+be sent to the port netdev for processing by the bridge driver.  The
 bridge should not reflood the packet to the same ports the device flooded,
 otherwise there will be duplicate packets on the wire.