staging: android: sync: Limit sync log dumping

Dump sync logs only when a fence is not signalled
for SYNC_DUMP_TIME_LIMIT or more. This is necessary
to reduce CPU hogging because of excessive sync logs
dumped due to fence timeouts which are less than
SYNC_DUMP_TIME_LIMIT and are harmless.

Change-Id: Id21a02925dd45a01361d096048a25d1879ebde9e
Signed-off-by: Deepak Kumar <dkumar@codeaurora.org>