dsa: mv88e6xxx: Enable forwarding for unknown to the CPU port

Frames destined to an unknown address must be forwarded to the CPU
port. Otherwise incoming ARP, dhcp leases, etc, do not work.
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/dsa/mv88e6xxx.c

@@ -2051,6 +2051,8 @@ static int mv88e6xxx_setup_port(struct dsa_switch *ds, int port)
 				reg |= PORT_CONTROL_FRAME_ETHER_TYPE_DSA;
 			else
 				reg |= PORT_CONTROL_FRAME_MODE_DSA;
+			reg |= PORT_CONTROL_FORWARD_UNKNOWN |
+				PORT_CONTROL_FORWARD_UNKNOWN_MC;
 		}
 
 		if (mv88e6xxx_6352_family(ds) || mv88e6xxx_6351_family(ds) ||