Input: atmel_mxt_ts - set pointer emulation on touchpads

Touchpads are pointers, so make sure to pass the correct values to
input_mt_report_pointer_emulation(). Without this, tap-to-click doesn't
work.

Signed-off-by: Benson Leung <bleung@chromium.org>
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Nick Dyer <nick.dyer@itdev.co.uk>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>