perf stat: Print out hint for mixed PMU group error

perf stat: Print out hint for mixed PMU group error

Perf doesn't support mixed events from different PMUs (except software
event) in a group. For this case, only "<not counted>" or "<not
supported>" are printed out. There is no hint which guides users to fix
the issue.

Checking the PMU type of events to determine if they are from the same
PMU. There may be false alarm for the checking. E.g. the core PMU has
different PMU type. But it should not happen often.

The false alarm can also be tolerated, because:

- It only happens on error path.
- It just provides a possible solution for the issue.

Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Cc: Agustin Vega-Frias <agustinv@codeaurora.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ganapatrao Kulkarni <ganapatrao.kulkarni@cavium.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Shaokun Zhang <zhangshaokun@hisilicon.com>
Cc: Will Deacon <will.deacon@arm.com>
Link: http://lkml.kernel.org/r/1524594014-79243-2-git-send-email-kan.liang@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>