[NETNS]: init dev_base_lock only once

* it already statically initialized
* reinitializing live global spinlock every time netns is
  setup is also wrong

Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/dev.c b/net/core/dev.c
index be6ceda..dd7e307 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4330,7 +4330,6 @@
 static int __net_init netdev_init(struct net *net)
 {
 	INIT_LIST_HEAD(&net->dev_base_head);
-	rwlock_init(&dev_base_lock);
 
 	net->dev_name_head = netdev_create_hash();
 	if (net->dev_name_head == NULL)