Previous changes separated the uses of pmu_event and pmu_metric,
however, both structures contained all the variables of event and
metric. This change removes the event variables from metric and the
metric variables from event.

Note, this change removes the setting of evsel's metric_name/expr as
these fields are no longer part of struct pmu_event. The metric
remains but is no longer implicitly requested when the event is. This
impacts a few Intel uncore events, however, as the ScaleUnit is shared
by the event and the metric this utility is questionable. Also the
MetricNames look broken (contain spaces) in some cases and when trying
to use the functionality with '-e' the metrics fail but regular
metrics with '-M' work. For example, on SkylakeX '-M' works:

```
$ perf stat -M LLC_MISSES.PCIE_WRITE -a sleep 1

 Performance counter stats for 'system wide':

                 0      UNC_IIO_DATA_REQ_OF_CPU.MEM_WRITE.PART2 #  57896.0 Bytes  LLC_MISSES.PCIE_WRITE  (49.84%)
             7,174      UNC_IIO_DATA_REQ_OF_CPU.MEM_WRITE.PART1                                        (49.85%)
                 0      UNC_IIO_DATA_REQ_OF_CPU.MEM_WRITE.PART3                                        (50.16%)
                63      UNC_IIO_DATA_REQ_OF_CPU.MEM_WRITE.PART0                                        (50.15%)

       1.004576381 seconds time elapsed
```

whilst the event '-e' version is broken even with --group/-g (fwiw, we should also remove -g [1]):

```
$ perf stat -g -e LLC_MISSES.PCIE_WRITE -g -a sleep 1
Add UNC_IIO_DATA_REQ_OF_CPU.MEM_WRITE.PART2 event to groups to get metric expression for LLC_MISSES.PCIE_WRITE
Add UNC_IIO_DATA_REQ_OF_CPU.MEM_WRITE.PART1 event to groups to get metric expression for LLC_MISSES.PCIE_WRITE
Add UNC_IIO_DATA_REQ_OF_CPU.MEM_WRITE.PART3 event to groups to get metric expression for LLC_MISSES.PCIE_WRITE
Add UNC_IIO_DATA_REQ_OF_CPU.MEM_WRITE.PART0 event to groups to get metric expression for LLC_MISSES.PCIE_WRITE
Add UNC_IIO_DATA_REQ_OF_CPU.MEM_WRITE.PART2 event to groups to get metric expression for LLC_MISSES.PCIE_WRITE
Add UNC_IIO_DATA_REQ_OF_CPU.MEM_WRITE.PART1 event to groups to get metric expression for LLC_MISSES.PCIE_WRITE
Add UNC_IIO_DATA_REQ_OF_CPU.MEM_WRITE.PART3 event to groups to get metric expression for LLC_MISSES.PCIE_WRITE
Add UNC_IIO_DATA_REQ_OF_CPU.MEM_WRITE.PART0 event to groups to get metric expression for LLC_MISSES.PCIE_WRITE
Add UNC_IIO_DATA_REQ_OF_CPU.MEM_WRITE.PART2 event to groups to get metric expression for LLC_MISSES.PCIE_WRITE
Add UNC_IIO_DATA_REQ_OF_CPU.MEM_WRITE.PART1 event to groups to get metric expression for LLC_MISSES.PCIE_WRITE
Add UNC_IIO_DATA_REQ_OF_CPU.MEM_WRITE.PART3 event to groups to get metric expression for LLC_MISSES.PCIE_WRITE
Add UNC_IIO_DATA_REQ_OF_CPU.MEM_WRITE.PART0 event to groups to get metric expression for LLC_MISSES.PCIE_WRITE
Add UNC_IIO_DATA_REQ_OF_CPU.MEM_WRITE.PART2 event to groups to get metric expression for LLC_MISSES.PCIE_WRITE
Add UNC_IIO_DATA_REQ_OF_CPU.MEM_WRITE.PART1 event to groups to get metric expression for LLC_MISSES.PCIE_WRITE
Add UNC_IIO_DATA_REQ_OF_CPU.MEM_WRITE.PART3 event to groups to get metric expression for LLC_MISSES.PCIE_WRITE
Add UNC_IIO_DATA_REQ_OF_CPU.MEM_WRITE.PART0 event to groups to get metric expression for LLC_MISSES.PCIE_WRITE
Add UNC_IIO_DATA_REQ_OF_CPU.MEM_WRITE.PART2 event to groups to get metric expression for LLC_MISSES.PCIE_WRITE
Add UNC_IIO_DATA_REQ_OF_CPU.MEM_WRITE.PART1 event to groups to get metric expression for LLC_MISSES.PCIE_WRITE
Add UNC_IIO_DATA_REQ_OF_CPU.MEM_WRITE.PART3 event to groups to get metric expression for LLC_MISSES.PCIE_WRITE
Add UNC_IIO_DATA_REQ_OF_CPU.MEM_WRITE.PART0 event to groups to get metric expression for LLC_MISSES.PCIE_WRITE
Add UNC_IIO_DATA_REQ_OF_CPU.MEM_WRITE.PART2 event to groups to get metric expression for LLC_MISSES.PCIE_WRITE
Add UNC_IIO_DATA_REQ_OF_CPU.MEM_WRITE.PART1 event to groups to get metric expression for LLC_MISSES.PCIE_WRITE
Add UNC_IIO_DATA_REQ_OF_CPU.MEM_WRITE.PART3 event to groups to get metric expression for LLC_MISSES.PCIE_WRITE
Add UNC_IIO_DATA_REQ_OF_CPU.MEM_WRITE.PART0 event to groups to get metric expression for LLC_MISSES.PCIE_WRITE

 Performance counter stats for 'system wide':

            27,316 Bytes LLC_MISSES.PCIE_WRITE

       1.004505469 seconds time elapsed
```

The code also carries warnings where the user is supposed to select
events for metrics [2] but given the lack of use of such a feature,
let's clean the code and just remove.

[1] https://lore.kernel.org/lkml/20220707195610.303254-1-irogers@google.com/
[2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/tools/perf/util/stat-shadow.c?id=01b8957b738f42f96a130079bc951b3cc78c5b8a#n425Reviewed-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: Kajol Jain <kjain@linux.ibm.com>
Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Caleb Biggers <caleb.biggers@intel.com>
Cc: Florian Fischer <florian.fischer@muhq.space>
Cc: Ian Rogers <irogers@google.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: Kan Liang <kan.liang@linux.intel.com>
Cc: Kang Minchul <tegongkang@gmail.com>
Cc: Kim Phillips <kim.phillips@amd.com>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Perry Taylor <perry.taylor@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: Rob Herring <robh@kernel.org>
Cc: Sandipan Das <sandipan.das@amd.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Will Deacon <will@kernel.org>
Cc: Xing Zhengjun <zhengjun.xing@linux.intel.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linuxppc-dev@lists.ozlabs.org
Link: https://lore.kernel.org/r/20230126233645.200509-7-irogers@google.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>