Input: allow certain EV_ABS events to bypass all filtering

With the upcoming multi-touch interface as an example, there is
a need to make certain that all reported events actually get passed
to the event handler. This patch equips the input core with the
ability to bypass all filtering for certain EV_ABS events.

Signed-off-by: Henrik Rydberg <rydberg@euromail.se>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>