perf tests: Fix Convert perf time to TSC test for hybrid

perf tests: Fix Convert perf time to TSC test for hybrid

The test does not always correctly determine the number of events for
hybrids, nor allow for more than 1 evsel when parsing.

Fix by iterating the events actually created and getting the correct
evsel for the events processed.

Fixes: c22669cd508cbd62 ("perf tests: Support 'Convert perf time to TSC' test for hybrid")
Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Thomas Richter <tmricht@linux.ibm.com>
Link: https://lore.kernel.org/r/20220713123459.24145-3-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>