Input: driver for microcontroller keys on the iPaq h3xxx

This adds a key input driver for the keys found on the h3xxx
iPAQ series.

Based on a driver from handhelds.org 2.6.21 kernel, written
by Alessandro GARDICH.

Signed-off-by: Alessandro GARDICH <gremlin@gremlin.it>
Signed-off-by: Dmitry Artamonow <mad_soft@inbox.ru>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>