Since for cpu_core or cpu_atom, they have different topdown events
groups.

For cpu_core, --topdown equals to:

"{slots,cpu_core/topdown-retiring/,cpu_core/topdown-bad-spec/,
  cpu_core/topdown-fe-bound/,cpu_core/topdown-be-bound/,
  cpu_core/topdown-heavy-ops/,cpu_core/topdown-br-mispredict/,
  cpu_core/topdown-fetch-lat/,cpu_core/topdown-mem-bound/}"

For cpu_atom, --topdown equals to:

"{cpu_atom/topdown-retiring/,cpu_atom/topdown-bad-spec/,
 cpu_atom/topdown-fe-bound/,cpu_atom/topdown-be-bound/}"

To simplify the implementation, on hybrid, --topdown is used
together with --cputype. If without --cputype, it uses cpu_core
topdown events by default.

  # ./perf stat --topdown -a  sleep 1
  WARNING: default to use cpu_core topdown events

   Performance counter stats for 'system wide':

              retiring      bad speculation       frontend bound        backend bound     heavy operations     light operations    branch mispredict       machine clears        fetch latency      fetch bandwidth         memory bound           Core bound
                  4.1%                 0.0%                 5.1%                90.8%                 2.3%                 1.8%                 0.0%                 0.0%                 4.2%                 0.9%                 9.9%                81.0%

         1.002624229 seconds time elapsed

  # ./perf stat --topdown -a --cputype atom  sleep 1

   Performance counter stats for 'system wide':

              retiring      bad speculation       frontend bound        backend bound
                 13.5%                 0.1%                31.2%                55.2%

         1.002366987 seconds time elapsed
Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Xing Zhengjun <zhengjun.xing@linux.intel.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220422065635.767648-3-zhengjun.xing@linux.intel.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>