Input: Avoid double unregistering of i8042 PnP driver. This can happen

       when no i8042 controller (not PnP, not legacy) is present.

From: Kurt Garloff <garloff@suse.de>
Signed-off-by: Vojtech Pavlik <vojtech@suse.cz>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>