perf report: Fix regression when decoding intel_pt traces

perf report: Fix regression when decoding intel_pt traces

Commit (93d10af26bb7 perf tools: Optimize sample parsing for ordered
events) breaks intelPT trace decoding by invariably returning an error
if the event type isn't a PERF_SAMPLE_TIME.

With this patch the timestamp is initialised and processing is allowed
to continue if the error returned by function
perf_evlist__parse_sample_timestamp() is not a fault.

Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Fixes: 93d10af26bb7 ("perf tools: Optimize sample parsing for ordered events")
Link: http://lkml.kernel.org/r/1515616312-27645-1-git-send-email-mathieu.poirier@linaro.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>