Input: HID - add mapping for Powerbook USB keyboard

Map custom HID events (such as the ones generated by some Logitech and
Apple Powerbooks USB keyboards) to the FN keycode.

Signed-off-by: Stelian Pop <stelian@popies.net>
Signed-off-by: Vojtech Pavlik <vojtech@suse.cz>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>