perf pmu: zfree() expects a pointer to a pointer to zero it after freeing its contents

An audit showed just this one problem with zfree(), fix it.

Fixes: 9fbc61f832 ("perf pmu: Add support for PMU capabilities")
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/pmu.c

@@ -1852,7 +1852,7 @@ static int perf_pmu__new_caps(struct list_head *list, char *name, char *value)
 	return 0;
 
 free_name:
-	zfree(caps->name);
+	zfree(&caps->name);
 free_caps:
 	free(caps);