Adjust Elantech signature validation to account fo rnewer models of
touchpads.

Cc: stable@vger.kernel.org
Reported-and-tested-by: Màrius Monton <marius.monton@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>