perf parse-events: Improve error message for double setting

Double setting information for an event would produce an error message
associated with the PMU rather than the term that was double setting.
Improve the error message to be on the term.

Before:

  $ perf stat -e 'cpu/inst_retired.any,inst_retired.any/' true
  event syntax error: 'cpu/inst_retired.any,inst_retired.any/'
                       \___ Bad event or PMU

  Unabled to find PMU or event on a PMU of 'cpu'
  Run 'perf list' for a list of valid events
  $

After:

  $ perf stat -e 'cpu/inst_retired.any,inst_retired.any/' true
  event syntax error: '..etired.any,inst_retired.any/'
                                    \___ Bad event or PMU

  Unabled to find PMU or event on a PMU of 'cpu'

  Initial error:

  event syntax error: '..etired.any,inst_retired.any/'
                                    \___ Attempt to set event's scale twice
  Run 'perf list' for a list of valid events

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: Gaosheng Cui <cuigaosheng1@huawei.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jing Zhang <renyu.zj@linux.alibaba.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Garry <john.g.garry@oracle.com>
Cc: Kajol Jain <kjain@linux.ibm.com>
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>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20230824041330.266337-6-irogers@google.com


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