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/drivers/net/wan/lapbether.c b/drivers/net/wan/lapbether.c
index a817081..7beeb9b 100644
--- a/drivers/net/wan/lapbether.c
+++ b/drivers/net/wan/lapbether.c
@@ -259,14 +259,13 @@
 }
 
 
-static struct lapb_register_struct lapbeth_callbacks = {
+static const struct lapb_register_struct lapbeth_callbacks = {
 	.connect_confirmation    = lapbeth_connected,
 	.connect_indication      = lapbeth_connected,
 	.disconnect_confirmation = lapbeth_disconnected,
 	.disconnect_indication   = lapbeth_disconnected,
 	.data_indication         = lapbeth_data_indication,
 	.data_transmit           = lapbeth_data_transmit,
-
 };
 
 /*