HID: wacom: Add support for DTU-1031X

Signed-off-by: Ping Cheng <pingc@wacom.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
diff --git a/drivers/hid/wacom_wac.h b/drivers/hid/wacom_wac.h
index 128cbb3..5384043 100644
--- a/drivers/hid/wacom_wac.h
+++ b/drivers/hid/wacom_wac.h
@@ -80,6 +80,7 @@
 	PL,
 	DTU,
 	DTUS,
+	DTUSX,
 	INTUOS,
 	INTUOS3S,
 	INTUOS3,