perf tests: Fix coresight perf test failure.

Currently the `perf test` always fails the coresight test like:

  89: Check Arm CoreSight trace data recording and synthesized samples: FAILED!

That is because the test_arm_coresight.sh is attempting to SIGINT the
parent but is using $$ rather than $PPID and it sigint's itself when
run under the perf test framework.

Since this is done in a trap clause it ends up returning a non zero
return.

Since $PPID is a bash ism and not all distros are linking /bin/sh to
bash, the alternative parent pid lookups are uglier than just dropping
the kill, and its not strictly needed, lets pick the simple solution and
drop the sigint.

Fixes: 133fe2e617 ("perf tests: Improve temp file cleanup in test_arm_coresight.sh")
Reviewed-by: James Clark <james.clark@arm.com>
Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Jeremy Linton <jeremy.linton@arm.com>
Link: https://lore.kernel.org/r/20220428151947.290146-1-jeremy.linton@arm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/tests/shell/test_arm_coresight.sh

@@ -29,7 +29,6 @@ cleanup_files()
 	rm -f ${file}
 	rm -f "${perfdata}.old"
 	trap - exit term int
-	kill -2 $$
 	exit $glb_err
 }