[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/net/sctp/protocol.c b/net/sctp/protocol.c
index c361deb..d4afafc 100644
--- a/net/sctp/protocol.c
+++ b/net/sctp/protocol.c
@@ -170,7 +170,7 @@
 	struct sctp_af *af;
 
 	read_lock(&dev_base_lock);
-	for (dev = dev_base; dev; dev = dev->next) {
+	for_each_netdev(dev) {
 		__list_for_each(pos, &sctp_address_families) {
 			af = list_entry(pos, struct sctp_af, list);
 			af->copy_addrlist(&sctp_local_addr_list, dev);