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: 133fe2e ("perf tests: Improve temp file cleanup in test_arm_coresight.sh")
Reviewed-by: James Clark <[email protected]>
Signed-off-by: Jeremy Linton <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Ian Rogers <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: James Clark <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Leo Yan <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Jeremy Linton <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

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
 }