net: dsa: Skip calling .port_vlan_filtering on no change

Even if VLAN filtering is global, DSA will call this callback once per
each port. Drivers should not have to compare the global state with the
requested change. So let DSA do it.
Signed-off-by: NVladimir Oltean <olteanv@gmail.com>
Reviewed-by: NAndrew Lunn <andrew@lunn.ch>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/dsa/port.c

@@ -203,6 +203,9 @@ int dsa_port_vlan_filtering(struct dsa_port *dp, bool vlan_filtering,
 	if (!dsa_port_can_apply_vlan_filtering(dp, vlan_filtering))
 		return -EINVAL;
 
+	if (dsa_port_is_vlan_filtering(dp) == vlan_filtering)
+		return 0;
+
 	err = ds->ops->port_vlan_filtering(ds, dp->index,
 					   vlan_filtering);
 	if (err)