vlan: Avoid hash table lookup to find group.

A struct net_device always maps to zero or one vlan groups and we
always know the device when we are looking up a group.  We currently
do a hash table lookup on the device to find the group but it is
much simpler to just store a pointer.

Signed-off-by: Jesse Gross <jesse@nicira.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 2861565..9c78312 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -942,7 +942,10 @@
 
 
 	/* Protocol specific pointers */
-	
+
+#if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
+	struct vlan_group	*vlgrp;		/* VLAN group */
+#endif
 #ifdef CONFIG_NET_DSA
 	void			*dsa_ptr;	/* dsa specific data */
 #endif