msm: kgsl: Allow tasks to signal pending events

Add a type parameter to event callbacks to give tasks a way to
communicate error conditions to the callback. Current type values
are KGSL_EVENT_TIMESTAMP_RETIRED for normal timestamp expiry and
KGSL_EVENT_CANCELLED if the event is cancelled prematurely.

Change-Id: Ic0dedbad9907cd50642a604a3af562e01a4b4a3b
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>