net: dsa: mv88e6xxx: skip unused ports

The unused ports are currently configured in normal mode. This does not
prevent the switch from being functional, but it is unnecessary. Skip
unused ports.
Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/dsa/mv88e6xxx/chip.c

@@ -2005,6 +2005,9 @@ static int mv88e6xxx_setup(struct dsa_switch *ds)
 
 	/* Setup Switch Port Registers */
 	for (i = 0; i < mv88e6xxx_num_ports(chip); i++) {
+		if (dsa_is_unused_port(ds, i))
+			continue;
+
 		err = mv88e6xxx_setup_port(chip, i);
 		if (err)
 			goto unlock;