wan: make read-only data const

Change several wan drivers to make strings and other initialize
only parameters const.

Compile tested only (with no new warnings)

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 4d4dc38..7f5bb91 100644
--- a/drivers/net/wan/lapbether.c
+++ b/drivers/net/wan/lapbether.c
@@ -46,7 +46,7 @@
 
 #include <net/x25device.h>
 
-static char bcast_addr[6] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
+static const u8 bcast_addr[6] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
 
 /* If this number is made larger, check that the temporary string buffer
  * in lapbeth_new_device is large enough to store the probe device name.*/