Input: ads7846 - use input_set_capability()

Instead of manipulating capability bits directly use
input_set_capability(). Also stop setting EV_ABS explicitly as
input_set_abs_params() does it for us.

Link: https://lore.kernel.org/r/20210910045039.4020199-2-dmitry.torokhov@gmail.com


Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>