When the device supports true hovering, it reports this
information through ABS_MT_DISTANCE.
When this axis is available, we should rely on it to
(un)hover the touches as BTN_TOUCH is most of the time
unreliable (generated by the mouse emulation in the kernel).
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@gmail.com>
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
