wan: make LAPB callbacks const

This is compile tested only.
Suggested by dumpster diving in PAX.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/lapb.h b/include/linux/lapb.h
index ce709e1..873c1eb 100644
--- a/include/linux/lapb.h
+++ b/include/linux/lapb.h
@@ -44,7 +44,8 @@
 	unsigned int mode;
 };
 
-extern int lapb_register(struct net_device *dev, struct lapb_register_struct *callbacks);
+extern int lapb_register(struct net_device *dev,
+			 const struct lapb_register_struct *callbacks);
 extern int lapb_unregister(struct net_device *dev);
 extern int lapb_getparms(struct net_device *dev, struct lapb_parms_struct *parms);
 extern int lapb_setparms(struct net_device *dev, struct lapb_parms_struct *parms);