perf python: In str(evsel) use the evsel__pmu_name helper

JIRA: https://issues.redhat.com/browse/RHEL-78198

upstream
========
commit 7d5b635
Author: Ian Rogers <irogers@google.com>
Date: Thu Jul 10 16:51:22 2025 -0700

description
===========
The evsel__pmu_name helper will internally use evsel__find_pmu that
handles legacy events, extended types, etc. in determining a PMU and
will provide a better value than just trying to access the PMU's name
directly as the PMU may not have been computed.

    Signed-off-by: Ian Rogers <irogers@google.com>
    Link: https://lore.kernel.org/r/20250710235126.1086011-10-irogers@google.com
    Signed-off-by: Namhyung Kim <namhyung@kernel.org>

Signed-off-by: Michael Petlan <mpetlan@redhat.com>

Author: rfmvh

tools/perf/util/python.c

@@ -925,10 +925,7 @@ static PyObject *pyrf_evsel__str(PyObject *self)
 	struct pyrf_evsel *pevsel = (void *)self;
 	struct evsel *evsel = &pevsel->evsel;
 
-	if (!evsel->pmu)
-		return PyUnicode_FromFormat("evsel(%s)", evsel__name(evsel));
-
-	return PyUnicode_FromFormat("evsel(%s/%s/)", evsel->pmu->name, evsel__name(evsel));
+	return PyUnicode_FromFormat("evsel(%s/%s/)", evsel__pmu_name(evsel), evsel__name(evsel));
 }
 
 static PyMethodDef pyrf_evsel__methods[] = {