selftests: hid: Add touch tests for Wacom devices

Adding a wacom touch device to use the test_multitouch tests.
Adding a 2 additional tests.
 - A test to check if a touch event is sent when the contact_id of the event is 0.
 - A test to check if a touch event is not sent when confidence is set to 0.

Signed-off-by: Joshua Dickens <joshua.dickens@wacom.com>
Reviewed-by: Jason Gerecke <jason.gerecke@wacom.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>