Rename the lists release_queue to release_list and event_list to
wait_list.

The prior names release_queue and event_list were ambiguous: in both are event-
like vblanks which can be removed from the lists in random order. In the
release_queue can be flips that are already released but still wait for the
sync or frame callback but normally the release comes later. In the event_list
are queued events waiting for a later msc.

Signed-off-by: Roman Gilg <subdiff@gmail.com>