Input: refactor evdev 32bit compat to be shareable with uinput

Currently, evdev has working 32bit compatibility and uinput does not. uinput
needs the input_event code that evdev uses, so let's refactor it so it can
be shared.

[dtor@mail.ru: add fix for force feedback compat issues]
Signed-off-by: Philip Langdale <philipl@overt.org>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>