HID: multitouch: fix protocol for Sitronix 1403:5001

Since the inclusion of this device in hid-multitouch, the device
did not forward any events. Using the serial class makes it working
again.
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/hid/hid-multitouch.c

@@ -1168,7 +1168,7 @@ static const struct hid_device_id mt_devices[] = {
 	{ .driver_data = MT_CLS_CONFIDENCE,
 		MT_USB_DEVICE(USB_VENDOR_ID_STANTUM_STM,
 			USB_DEVICE_ID_MTP_STM)},
-	{ .driver_data = MT_CLS_CONFIDENCE,
+	{ .driver_data = MT_CLS_ALWAYS_TRUE,
 		MT_USB_DEVICE(USB_VENDOR_ID_STANTUM_SITRONIX,
 			USB_DEVICE_ID_MTP_SITRONIX)},