greth: Use return value of register_netdev

Use the return value provided by register_netdev on error instead of
hard setting it to -ENOMEM.
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/greth.c

@@ -1547,10 +1547,10 @@ static int __devinit greth_of_probe(struct platform_device *ofdev, const struct
 	dev->netdev_ops = &greth_netdev_ops;
 	dev->ethtool_ops = &greth_ethtool_ops;
 
-	if (register_netdev(dev)) {
+	err = register_netdev(dev);
+	if (err) {
 		if (netif_msg_probe(greth))
 			dev_err(greth->dev, "netdevice registration failed.\n");
-		err = -ENOMEM;
 		goto error5;
 	}