Input: synaptics - enable InterTouch for ThinkPad X1E 1st gen

Tested on my own laptop, touchpad feels slightly more responsive with
this on, though it might just be placebo.

Signed-off-by: Ilya Katsnelson <me@0upti.me>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Link: https://lore.kernel.org/r/20200703143457.132373-1-me@0upti.me
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/mouse/synaptics.c

@@ -179,6 +179,7 @@ static const char * const smbus_pnp_ids[] = {
 	"LEN0093", /* T480 */
 	"LEN0096", /* X280 */
 	"LEN0097", /* X280 -> ALPS trackpoint */
+	"LEN0099", /* X1 Extreme 1st */
 	"LEN009b", /* T580 */
 	"LEN200f", /* T450s */
 	"LEN2044", /* L470  */