perf parse-events: Support different format of the topdown event name

perf parse-events: Support different format of the topdown event name

The evsel->name may have a different format for a topdown event, a pure
topdown name (e.g., topdown-fe-bound), or a PMU name + a topdown name
(e.g., cpu/topdown-fe-bound/). The cpu/topdown-fe-bound/ kind format
isn't supported by the arch_evlist__leader(). This format is a very
common format for a hybrid platform, which requires specifying the PMU
name for each event.

Without the patch,

  $ perf stat -e '{instructions,slots,cpu/topdown-fe-bound/}' -a sleep 1

   Performance counter stats for 'system wide':

       <not counted>      instructions
       <not counted>      slots
     <not supported>      cpu/topdown-fe-bound/

         1.003482041 seconds time elapsed

  Some events weren't counted. Try disabling the NMI watchdog:
          echo 0 > /proc/sys/kernel/nmi_watchdog
          perf stat ...
          echo 1 > /proc/sys/kernel/nmi_watchdog
  The events in group usually have to be from the same PMU. Try reorganizing the group.

With the patch,

  $ perf stat -e '{instructions,slots,cpu/topdown-fe-bound/}' -a sleep 1

  Performance counter stats for 'system wide':

         157,383,996      slots
          25,011,711      instructions
          27,441,686      cpu/topdown-fe-bound/

         1.003530890 seconds time elapsed

Fixes: bc355822f0d9623b ("perf parse-events: Move slots only with topdown")
Reviewed-by: Ian Rogers <irogers@google.com>
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Cc: Adrian Hunter <adrian.hunter@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: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Xing Zhengjun <zhengjun.xing@linux.intel.com>
Link: https://lore.kernel.org/r/20220518143900.1493980-4-kan.liang@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>