Input: synaptics - add Lenovo 80 series ids to SMBus

commit ad8fb554f0 upstream.

This time, Lenovo decided to go with different pieces in its latest
series of Thinkpads.

For those we have been able to test:
- the T480 is using Synaptics with an IBM trackpoint
   -> it behaves properly with or without intertouch, there is no point
      not using RMI4
- the X1 Carbon 6th gen is using Synaptics with an IBM trackpoint
   -> the touchpad doesn't behave properly under PS/2 so we have to
      switch it to RMI4 if we do not want to have disappointed users
- the X280 is using Synaptics with an ALPS trackpoint
   -> the recent fixes in the trackpoint handling fixed it so upstream
      now works fine with or without RMI4, and there is no point not
      using RMI4
- the T480s is using an Elan touchpad, so that's a different story

Cc: <stable@vger.kernel.org> # v4.14.x, v4.15.x, v4.16.x
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Acked-by: KT Liao <kt.liao@emc.com.tw>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/input/mouse/synaptics.c

@@ -172,10 +172,12 @@ static const char * const smbus_pnp_ids[] = {
 	"LEN0048", /* X1 Carbon 3 */
 	"LEN0046", /* X250 */
 	"LEN004a", /* W541 */
+	"LEN0071", /* T480 */
 	"LEN0072", /* X1 Carbon Gen 5 (2017) - Elan/ALPS trackpoint */
 	"LEN0073", /* X1 Carbon G5 (Elantech) */
 	"LEN0092", /* X1 Carbon 6 */
 	"LEN0096", /* X280 */
+	"LEN0097", /* X280 -> ALPS trackpoint */
 	"LEN200f", /* T450s */
 	NULL
 };