dsa/mv88e6131: fix unknown multicast/broadcast forwarding on mv88e6085

The 88e6085 has a few differences from the other devices in the port
control registers, causing unknown multicast/broadcast packets to get
dropped when using the standard port setup.

At the same time update kconfig to clarify that the mv88e6085 is now
supported.

Signed-off-by: Peter Korsgaard <[email protected]>
Acked-by: Lennert Buytenhek <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
2 files changed