drm/msm/sde: add pending retire fence count to event logs

Add the pending retire fence count to the event logs. This
will make it easier to track sde fence signalling issues
in the future.

Change-Id: Ib6e5e45f524f4cd7e32b7e2b529b086a511e0b80
Signed-off-by: Fuad Hossain <fhossain@codeaurora.org>