perf pmu: Improve name/comments, avoid a memory allocation

Improve documentation around perf_pmu_alias pmu_name and on
functions.

Reduce the scope of pmu_uncore_alias_match to just file.

Rename perf_pmu__valid_suffix to the more revealing
perf_pmu__match_ignoring_suffix.

Add a short-cut to perf_pmu__match_ignoring_suffix for PMU names that
don't also have a socket value, and can therefore avoid a memory
allocation.

Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
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>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Suzuki Poulouse <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20230406235256.2768773-1-irogers@google.com


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