net_namespace: trivial cleanup

Do not initialize net_kill_list twice.
list_replace_init() already takes care of initializing net_kill_list.
We don't need to initialize it with LIST_HEAD() beforehand.
Signed-off-by: Nxiao jin <jin.xiao@intel.com>
Reviewed-by: NDavid Cohen <david.a.cohen@linux.intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/core/net_namespace.c

@@ -273,7 +273,7 @@ static void cleanup_net(struct work_struct *work)
 {
 	const struct pernet_operations *ops;
 	struct net *net, *tmp;
-	LIST_HEAD(net_kill_list);
+	struct list_head net_kill_list;
 	LIST_HEAD(net_exit_list);
 
 	/* Atomically snapshot the list of namespaces to cleanup */