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>