perf evsel: Fix uniquification when PMU given without suffix

perf evsel: Fix uniquification when PMU given without suffix

The PMU name is appearing twice in:
```
$ perf stat -e uncore_imc_free_running/data_total/ -A true

 Performance counter stats for 'system wide':

CPU0                 1.57 MiB  uncore_imc_free_running_0/uncore_imc_free_running,data_total/
CPU0                 1.58 MiB  uncore_imc_free_running_1/uncore_imc_free_running,data_total/
       0.000892376 seconds time elapsed
```

Use the pmu_name_len_no_suffix to avoid this problem.

Committer testing:

After this patch:

  root@x1:~# perf stat -e uncore_imc_free_running/data_total/ -A true

   Performance counter stats for 'system wide':

  CPU0                 1.69 MiB  uncore_imc_free_running_0/data_total/
  CPU0                 1.68 MiB  uncore_imc_free_running_1/data_total/

         0.002141605 seconds time elapsed

  root@x1:~#

Fixes: 7d45f402d3117e0b ("perf evlist: Make uniquifying counter names consistent")
Signed-off-by: Ian Rogers <irogers@google.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Athira Rajeev <atrajeev@linux.ibm.com>
Cc: Chun-Tse Shao <ctshao@google.com>
Cc: Howard Chu <howardchu95@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>