perf tests: Stop Convert perf time to TSC test opening events twice

Do not call evlist__open() twice.

Fixes: 5bb017d4 ("perf test: Fix error message for test case 71 on s390, where it is not supported")
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: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Thomas Richter <tmricht@linux.ibm.com>
Link: https://lore.kernel.org/r/20220713123459.24145-2-adrian.hunter@intel.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/tests/perf-time-to-tsc.c

@@ -123,11 +123,14 @@ static int test__perf_time_to_tsc(struct test_suite *test __maybe_unused, int su
 		evsel->core.attr.enable_on_exec = 0;
 	}
 
-	if (evlist__open(evlist) == -ENOENT) {
+	ret = evlist__open(evlist);
+	if (ret < 0) {
+		if (ret == -ENOENT)
 			err = TEST_SKIP;
+		else
+			pr_debug("evlist__open() failed\n");
 		goto out_err;
 	}
-	CHECK__(evlist__open(evlist));
 
 	CHECK__(evlist__mmap(evlist, UINT_MAX));