HID: multitouch: Add required quirk for Synaptics 0xcd7e device

Register the Synaptics device as a special multitouch device with certain
quirks that may improve usability of the touchpad device.

Reported-by: Rain <rain@sunshowers.io>
Closes: https://lore.kernel.org/linux-input/2bbb8e1d-1793-4df1-810f-cb0137341ff4@app.fastmail.com/
Signed-off-by: Rahul Rameshbabu <sergeantsagara@protonmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

Author: Binary-Eater

drivers/hid/hid-multitouch.c

@@ -2144,6 +2144,10 @@ static const struct hid_device_id mt_devices[] = {
 			USB_DEVICE_ID_MTP_STM)},
 
 	/* Synaptics devices */
+	{ .driver_data = MT_CLS_WIN_8_FORCE_MULTI_INPUT,
+		HID_DEVICE(BUS_I2C, HID_GROUP_MULTITOUCH_WIN_8,
+			USB_VENDOR_ID_SYNAPTICS, 0xcd7e) },
+
 	{ .driver_data = MT_CLS_WIN_8_FORCE_MULTI_INPUT,
 		HID_DEVICE(BUS_I2C, HID_GROUP_MULTITOUCH_WIN_8,
 			USB_VENDOR_ID_SYNAPTICS, 0xce08) },