Input: export various input device attributes via sysfs

The following structure is exported:

  input0/
	|-- name
	|-- phys
	|-- uniq
	|-- id/{bustype|vendor|product|version}
	`-- capabilities/{ev|abs|rel|key|led|msc|ff|sw}
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>