perf tests: Fix coresight `perf test` failure.

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: 133fe2e617e48ca0 ("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>