Input: atmel_mxt_ts - add T100 as a readable object

When using the 'object' sysfs attribute, T100 is not displayed in
the output.

Signed-off-by: Maxime Roussin-Bélanger <maxime.roussinbelanger@gmail.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>