[NET]: Rework dev_base via list_head (v3)

Cleanup of dev_base list use, with the aim to simplify making device
list per-namespace. In almost every occasion, use of dev_base variable
and dev->next pointer could be easily replaced by for_each_netdev
loop. A few most complicated places were converted to using
first_netdev()/next_netdev().

Signed-off-by: Pavel Emelianov <xemul@openvz.org>
Acked-by: Kirill Korotaev <dev@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/parisc/led.c b/drivers/parisc/led.c
index 3df82fe..98be288 100644
--- a/drivers/parisc/led.c
+++ b/drivers/parisc/led.c
@@ -365,7 +365,7 @@
 	 * for reading should be OK */
 	read_lock(&dev_base_lock);
 	rcu_read_lock();
-	for (dev = dev_base; dev; dev = dev->next) {
+	for_each_netdev(dev) {
 	    struct net_device_stats *stats;
 	    struct in_device *in_dev = __in_dev_get_rcu(dev);
 	    if (!in_dev || !in_dev->ifa_list)