net: Fix call to ->change_rx_flags(dev, IFF_MULTICAST) in dev_change_flags()

Am I just being particularly dim today, or can the call to
dev->change_rx_flags(dev, IFF_MULTICAST) in dev_change_flags() never
happen?

We've just set dev->flags = flags & IFF_MULTICAST, effectively. So the
condition '(dev->flags ^ flags) & IFF_MULTICAST' is _never_ going to be
true.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/dev.c

@@ -3141,7 +3141,7 @@ int dev_change_flags(struct net_device *dev, unsigned flags)
 	 *	Load in the correct multicast list now the flags have changed.
 	 */
 
-	if (dev->change_rx_flags && (dev->flags ^ flags) & IFF_MULTICAST)
+	if (dev->change_rx_flags && (old_flags ^ flags) & IFF_MULTICAST)
 		dev->change_rx_flags(dev, IFF_MULTICAST);
 
 	dev_set_rx_mode(dev);