Input: wacom_serial4 - constify serio_device_id

serio_device_id are not supposed to change at runtime. All functions
working with serio_device_id provided by <linux/serio.h> work with
const serio_device_id. So mark the non-const structs as const.

Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/tablet/wacom_serial4.c

@@ -594,7 +594,7 @@ free_device:
 	return err;
 }
 
-static struct serio_device_id wacom_serio_ids[] = {
+static const struct serio_device_id wacom_serio_ids[] = {
 	{
 		.type	= SERIO_RS232,
 		.proto	= SERIO_WACOM_IV,