Input: synaptics - enable SMBus for HP 15-ay000

SMBus works fine for the touchpad with id SYN3221, used in the HP 15-ay000
series,

This device has been reported in these messages in the "linux-input"
mailing list:
* https://marc.info/?l=linux-input&m=152016683003369&w=2
* https://www.spinics.net/lists/linux-input/msg52525.html

Reported-by: Nitesh Debnath <niteshkd1999@gmail.com>
Reported-by: Teika Kazura <teika@gmx.com>
Signed-off-by: Teika Kazura <teika@gmx.com>
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/mouse/synaptics.c

@@ -178,6 +178,7 @@ static const char * const smbus_pnp_ids[] = {
 	"LEN0096", /* X280 */
 	"LEN0097", /* X280 -> ALPS trackpoint */
 	"LEN200f", /* T450s */
+	"SYN3221", /* HP 15-ay000 */
 	NULL
 };