perf metricgroup: Fix metrics using aliases covering multiple PMUs

Support for metric expressions using aliases which cover multiple PMUs
is broken. Consider the following test metric expression:

  "MetricExpr": "UNC_CBO_XSNP_RESPONSE.MISS_XCORE * UNC_CBO_XSNP_RESPONSE.MISS_EVICTION"

When used on my broadwell, "perf stat" gives:

  unc_cbo_xsnp_response.miss_eviction -> uncore_cbox_1/umask=0x81,event=0x22/
  unc_cbo_xsnp_response.miss_eviction -> uncore_cbox_0/umask=0x81,event=0x22/
  unc_cbo_xsnp_response.miss_xcore -> uncore_cbox_1/umask=0x41,event=0x22/
  unc_cbo_xsnp_response.miss_xcore -> uncore_cbox_0/umask=0x41,event=0x22/
  Control descriptor is not initialized
  unc_cbo_xsnp_response.miss_eviction: 3645925 1000850523 1000850523
  unc_cbo_xsnp_response.miss_xcore: 106850 1000850523 1000850523

   Performance counter stats for 'system wide':

           3,645,925      unc_cbo_xsnp_response.miss_eviction # 389567086250.00 test_metric_inc
             106,850      unc_cbo_xsnp_response.miss_xcore

         1.000883096 seconds time elapsed

Notice that only the results from one PMU are included. Fix the logic of
find_evsel_group() to enable events which apply to multiple PMUs, by
checking if the event pmu_name matches that of the metric event.

With that, "perf stat" now gives:

  unc_cbo_xsnp_response.miss_eviction -> uncore_cbox_1/umask=0x81,event=0x22/
  unc_cbo_xsnp_response.miss_eviction -> uncore_cbox_0/umask=0x81,event=0x22/
  unc_cbo_xsnp_response.miss_xcore -> uncore_cbox_1/umask=0x41,event=0x22/
  unc_cbo_xsnp_response.miss_xcore -> uncore_cbox_0/umask=0x41,event=0x22/
  Control descriptor is not initialized
  unc_cbo_xsnp_response.miss_eviction: 4237983 1000904100 1000904100
  unc_cbo_xsnp_response.miss_xcore: 218643 1000904100 1000904100
  unc_cbo_xsnp_response.miss_eviction: 4254148 1000902629 1000902629
  unc_cbo_xsnp_response.miss_xcore: 213352 1000902629 1000902629

   Performance counter stats for 'system wide':

           4,237,983      unc_cbo_xsnp_response.miss_eviction # 3668558131345.00 test_metric_inc
             218,643      unc_cbo_xsnp_response.miss_xcore
           4,254,148      unc_cbo_xsnp_response.miss_eviction
             213,352      unc_cbo_xsnp_response.miss_xcore

         1.000938151 seconds time elapsed

Signed-off-by: John Garry <john.garry@huawei.com>
Acked-by: Kajol Jain <kjain@linux.ibm.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Joakim Zhang <qiangqing.zhang@nxp.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Kim Phillips <kim.phillips@amd.com>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Shaokun Zhang <zhangshaokun@hisilicon.com>
Cc: Will Deacon <will@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linuxarm@huawei.com
Link: http://lore.kernel.org/lkml/1607080216-36968-7-git-send-email-john.garry@huawei.com


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>