net-next: dsa: make the set_addr() operation optional

Only 1 of the 3 drivers currently has a set_addr() operation. Make the
set_addr() callback optional to reduce the amount of empty stubs inside
the drivers.
Signed-off-by: John Crispin <john@phrozen.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/dsa/dsa.c

@@ -378,9 +378,11 @@ static int dsa_switch_setup_one(struct dsa_switch *ds, struct device *parent)
 	if (ret < 0)
 		goto out;
 
-	ret = ops->set_addr(ds, dst->master_netdev->dev_addr);
-	if (ret < 0)
-		goto out;
+	if (ops->set_addr) {
+		ret = ops->set_addr(ds, dst->master_netdev->dev_addr);
+		if (ret < 0)
+			goto out;
+	}
 
 	if (!ds->slave_mii_bus && ops->phy_read) {
 		ds->slave_mii_bus = devm_mdiobus_alloc(parent);

net/dsa/dsa2.c

@@ -304,9 +304,11 @@ static int dsa_ds_apply(struct dsa_switch_tree *dst, struct dsa_switch *ds)
 	if (err < 0)
 		return err;
 
-	err = ds->ops->set_addr(ds, dst->master_netdev->dev_addr);
-	if (err < 0)
-		return err;
+	if (ds->ops->set_addr) {
+		err = ds->ops->set_addr(ds, dst->master_netdev->dev_addr);
+		if (err < 0)
+			return err;
+	}
 
 	if (!ds->slave_mii_bus && ds->ops->phy_read) {
 		ds->slave_mii_bus = devm_mdiobus_alloc(ds->dev);