HID: asus: Add T100TA touchpad resolution info

The touchpad code is only used with the T100TA touchpad which
measures 75.5 x 41.5 mm, add corresponding resolution info.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>