net: make dev_close and related functions void

There is no useful return value from dev_close. All paths return 0.
Change dev_close and helper functions to void.

Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index c60351b..614642e 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -2432,8 +2432,8 @@ struct net_device *dev_get_by_name_rcu(struct net *net, const char *name);
 struct net_device *__dev_get_by_name(struct net *net, const char *name);
 int dev_alloc_name(struct net_device *dev, const char *name);
 int dev_open(struct net_device *dev);
-int dev_close(struct net_device *dev);
-int dev_close_many(struct list_head *head, bool unlink);
+void dev_close(struct net_device *dev);
+void dev_close_many(struct list_head *head, bool unlink);
 void dev_disable_lro(struct net_device *dev);
 int dev_loopback_xmit(struct net *net, struct sock *sk, struct sk_buff *newskb);
 int dev_queue_xmit(struct sk_buff *skb);