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/x25_asy.c b/drivers/net/wan/x25_asy.c
index 46ceb3a..8a10bb7 100644
--- a/drivers/net/wan/x25_asy.c
+++ b/drivers/net/wan/x25_asy.c
@@ -434,14 +434,13 @@
 	netif_rx(skb);
 }
 
-static struct lapb_register_struct x25_asy_callbacks = {
+static const struct lapb_register_struct x25_asy_callbacks = {
 	.connect_confirmation = x25_asy_connected,
 	.connect_indication = x25_asy_connected,
 	.disconnect_confirmation = x25_asy_disconnected,
 	.disconnect_indication = x25_asy_disconnected,
 	.data_indication = x25_asy_data_indication,
 	.data_transmit = x25_asy_data_transmit,
-
 };