Input: elantech - enable middle button of touchpad on ThinkPad P72

Adding 2 new touchpad IDs to support middle button support.

Cc: stable@vger.kernel.org
Signed-off-by: NAaron Ma <aaron.ma@canonical.com>
Signed-off-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/mouse/elantech.c

@@ -1178,6 +1178,8 @@ static const struct dmi_system_id elantech_dmi_has_middle_button[] = {
 static const char * const middle_button_pnp_ids[] = {
 	"LEN2131", /* ThinkPad P52 w/ NFC */
 	"LEN2132", /* ThinkPad P52 */
+	"LEN2133", /* ThinkPad P72 w/ NFC */
+	"LEN2134", /* ThinkPad P72 */
 	NULL
 };