net: dsa: mv88e6xxx: silently accept the deletion of VID 0 too

The blamed commit modified the driver to accept the addition of VID 0
without doing anything, but deleting that VID still fails:

[   32.080780] mv88e6085 d0032004.mdio-mii:10 lan8: failed to kill vid 0081/0

Modify mv88e6xxx_port_vlan_leave() to do the same thing as the addition.

Fixes: b8b79c41 ("net: dsa: mv88e6xxx: Fix adding vlan 0")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/dsa/mv88e6xxx/chip.c

@@ -2155,7 +2155,7 @@ static int mv88e6xxx_port_vlan_leave(struct mv88e6xxx_chip *chip,
 	int i, err;
 
 	if (!vid)
-		return -EOPNOTSUPP;
+		return 0;
 
 	err = mv88e6xxx_vtu_get(chip, vid, &vlan);
 	if (err)