perf stat: Warn group events from different hybrid PMU

If a group has events which are from different hybrid PMUs,
shows a warning:

"WARNING: events in group from different hybrid PMUs!"

This is to remind the user not to put the core event and atom
event into one group.

Next, just disable grouping.

  # perf stat -e "{cpu_core/cycles/,cpu_atom/cycles/}" -a -- sleep 1
  WARNING: events in group from different hybrid PMUs!
  WARNING: grouped events cpus do not match, disabling group:
    anon group { cpu_core/cycles/, cpu_atom/cycles/ }

   Performance counter stats for 'system wide':

           5,438,125      cpu_core/cycles/
           3,914,586      cpu_atom/cycles/

         1.004250966 seconds time elapsed

Signed-off-by: Jin Yao <yao.jin@linux.intel.com>
Reviewed-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20210427070139.25256-17-yao.jin@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>