Input: input-polldev, matrix-keypad - include in kernel doc

Make sure that polled input device and matrix keypad APIs are included
with the rest of input API when generating kernel documentation. Also
description of absres was missing as well.

Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

include/linux/input.h

@@ -1040,6 +1040,7 @@ struct ff_effect {
  * @absmin: minimum values for events coming from absolute axes
  * @absfuzz: describes noisiness for axes
  * @absflat: size of the center flat position (used by joydev)
+ * @absres: resolution used for events coming form absolute axes
  * @open: this method is called when the very first user calls
  *	input_open_device(). The driver must prepare the device
  *	to start generating events (start polling thread,