[NET]: unregister_netdevice as void

There was no real useful information from the unregister_netdevice() return
code, the only error occurred in a situation that was a driver bug. So
change it to a void function.

Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 2e37f50..1a52854 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -589,7 +589,7 @@
 extern int		dev_close(struct net_device *dev);
 extern int		dev_queue_xmit(struct sk_buff *skb);
 extern int		register_netdevice(struct net_device *dev);
-extern int		unregister_netdevice(struct net_device *dev);
+extern void		unregister_netdevice(struct net_device *dev);
 extern void		free_netdev(struct net_device *dev);
 extern void		synchronize_net(void);
 extern int 		register_netdevice_notifier(struct notifier_block *nb);