perf test: test_intel_pt.sh: Use a temp directory

perf test: test_intel_pt.sh: Use a temp directory

Create a directory for temporary files so that mktemp needs to be used
only once. It also enables more temp files to be added without having to
add them also to the cleanup.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20220912083412.7058-3-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>