perf tests: Make data symbol test wait for perf to start

perf tests: Make data symbol test wait for perf to start

The perf data symbol test waits 1 second for perf to run and collect data,
which may be too little if perf takes a long time to start up, which has
been noticed on systems with many CPUs. Use existing wait_for_perf_to_start
helper to wait for perf to start.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Acked-by: Ian Rogers <irogers@google.com>
Cc: German Gomez <german.gomez@arm.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20231123075848.9652-8-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>