net: Allow devices to specify a device specific sysfs group.

This isn't beautifully abstracted, but it is simple,
simplifies uses and so far is only needed for the bonding driver.

Signed-off-by: Eric W. Biederman <ebiederm@aristanetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 193b637..e5ece8d 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -900,8 +900,8 @@
 
 	/* class/net/name entry */
 	struct device		dev;
-	/* space for optional statistics and wireless sysfs groups */
-	const struct attribute_group *sysfs_groups[3];
+	/* space for optional device, statistics, and wireless sysfs groups */
+	const struct attribute_group *sysfs_groups[4];
 
 	/* rtnetlink link ops */
 	const struct rtnl_link_ops *rtnl_link_ops;