perf test: Fix perf stat JSON output test

perf test: Fix perf stat JSON output test

The recent --per-cache option test caused a problem.  According to the
option name, I think it should check args.per_cache instead of
args.per_cache_instance.

  $ sudo ./perf test -v 99
   99: perf stat JSON output linter                                    :
  --- start ---
  test child forked, pid 3086101
  Checking json output: no args [Success]
  Checking json output: system wide [Success]
  Checking json output: interval [Success]
  Checking json output: event [Success]
  Checking json output: per thread [Success]
  Checking json output: per node [Success]
  Checking json output: system wide no aggregation [Success]
  Checking json output: per core [Success]
  Checking json output: per cache_instance Test failed for input:
  ...
  Traceback (most recent call last):
    File "linux/tools/perf/tests/shell/lib/perf_json_output_lint.py", line 88, in <module>
      elif args.per_core or args.per_socket or args.per_node or args.per_die or args.per_cache_instance:
  AttributeError: 'Namespace' object has no attribute 'per_cache_instance'
  test child finished with -1
  ---- end ----
  perf stat JSON output linter: FAILED!

Fixes: bfce728db3179042 ("pert tests: Add tests for new "perf stat --per-cache" aggregation option")
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Acked-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230524210600.3095830-1-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>