Input: xen-kbdfront - make xenbus device ids constant

The ids field of the struct xenbus_device_id is constant in <linux/xen/xenbus.h>
so it makes sense to mark xenkbd_ids also constant.

Signed-off-by: Márton Németh <nm127@freemail.hu>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
diff --git a/drivers/input/xen-kbdfront.c b/drivers/input/xen-kbdfront.c
index c721c0a..d30436f 100644
--- a/drivers/input/xen-kbdfront.c
+++ b/drivers/input/xen-kbdfront.c
@@ -321,7 +321,7 @@
 	}
 }
 
-static struct xenbus_device_id xenkbd_ids[] = {
+static const struct xenbus_device_id xenkbd_ids[] = {
 	{ "vkbd" },
 	{ "" }
 };