Introduced in 416fa44d

 but there was a logic
error: we claimed to require 3 events from a trackpoint before stopping the
touchpad but the timer was only set when we actually stopped the touchpad. So
if a trackpoint sends a single event every second, we'd disable the touchpad
after 3 seconds for the duration of the timeout, then again 3 seconds later,
etc.

Fix this by always setting the timeout and resetting the event counter if no
activity happened.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
(cherry picked from commit c0fd857d)