Input: tca8418 - switch to using generic device properties

Let's drop legacy platform data support (there are no users in mainline)
and switch to using generic device properties, which will make the driver
simpler (non-OF boards can use property sets to describe hardware).

Reviewed-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>