HID: multitouch: support buttons and trackpoint on Lenovo X1 Tab Gen2

On the 2nd generation Lenovo Tablet only clickpad is working; the
trackpoint and three mouse buttons do not work.

hid_multitouch must export all inputs in order to get trackpoint and
buttons to function.
Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/hid/hid-ids.h

@@ -661,6 +661,7 @@
 #define USB_DEVICE_ID_LENOVO_CBTKBD	0x6048
 #define USB_DEVICE_ID_LENOVO_TPPRODOCK	0x6067
 #define USB_DEVICE_ID_LENOVO_X1_COVER	0x6085
+#define USB_DEVICE_ID_LENOVO_X1_TAB	0x60a3
 
 #define USB_VENDOR_ID_LG		0x1fd2
 #define USB_DEVICE_ID_LG_MULTITOUCH	0x0064

drivers/hid/hid-multitouch.c

@@ -1420,6 +1420,12 @@ static const struct hid_device_id mt_devices[] = {
 			USB_VENDOR_ID_ALPS_JP,
 			HID_DEVICE_ID_ALPS_U1_DUAL_3BTN_PTP) },
 
+	/* Lenovo X1 TAB Gen 2 */
+	{ .driver_data = MT_CLS_WIN_8_DUAL,
+		HID_DEVICE(BUS_USB, HID_GROUP_MULTITOUCH_WIN_8,
+			   USB_VENDOR_ID_LENOVO,
+			   USB_DEVICE_ID_LENOVO_X1_TAB) },
+
 	/* Anton devices */
 	{ .driver_data = MT_CLS_EXPORT_ALL_INPUTS,
 		MT_USB_DEVICE(USB_VENDOR_ID_ANTON,