HID: multitouch: support for hovering devices

Win8 devices supporting hovering must provides InRange HID field.
The information that the finger is here but is not touching the surface
is sent to the user space through ABS_MT_DISTANCE as required by the
multitouch protocol.

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@gmail.com>
Reviewed-by: Henrik Rydberg <rydberg@euromail.se>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>