[IPV4]: When possible test for IFF_LOOPBACK and not dev == loopback_dev

Now that multiple loopback devices are becoming possible it makes
the code a little cleaner and more maintainable to test if a deivice
is th a loopback device by testing dev->flags & IFF_LOOPBACK instead
of dev == loopback_dev.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/ipconfig.c b/net/ipv4/ipconfig.c
index 2d2e0cd..af5d5b3 100644
--- a/net/ipv4/ipconfig.c
+++ b/net/ipv4/ipconfig.c
@@ -190,11 +190,15 @@
 	rtnl_lock();
 
 	/* bring loopback device up first */
-	if (dev_change_flags(loopback_dev, loopback_dev->flags | IFF_UP) < 0)
-		printk(KERN_ERR "IP-Config: Failed to open %s\n", loopback_dev->name);
+	for_each_netdev(&init_net, dev) {
+		if (!(dev->flags & IFF_LOOPBACK))
+			continue;
+		if (dev_change_flags(dev, dev->flags | IFF_UP) < 0)
+			printk(KERN_ERR "IP-Config: Failed to open %s\n", dev->name);
+	}
 
 	for_each_netdev(&init_net, dev) {
-		if (dev == loopback_dev)
+		if (dev->flags & IFF_LOOPBACK)
 			continue;
 		if (user_dev_name[0] ? !strcmp(dev->name, user_dev_name) :
 		    (!(dev->flags & IFF_LOOPBACK) &&