Input: synaptics - whitelist Lenovo T580 SMBus intertouch

Adds the Lenovo T580 to the SMBus intertouch list for Synaptics
touchpads. I've tested with this for a week now, and it seems a great
improvement. It's also nice to have the complaint gone from dmesg.

Signed-off-by: Nick Black <dankamongmen@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>