Input: st1232 - add reset pin handling

We add the possibility to hand over a GPIO number for the reset pin.
This way we can remove existing board code that takes care of it and
group this information properly in the platform data or in the device
tree configuration.

Signed-off-by: Bastian Hecht <hechtb+renesas@gmail.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>