perf metrics: Use 'unsigned int' instead of just 'unsigned'.

'unsigned int' should be clearer than 'unsigned'.
Signed-off-by: Xin Gao <gaoxin@cdjrlc.com>
Cc: Ian Rogers <irogers@google.com>
Cc: John Garry <john.garry@huawei.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20220816173804.7539-1-gaoxin@cdjrlc.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/metricgroup.c

@@ -1703,7 +1703,7 @@ int metricgroup__copy_metric_events(struct evlist *evlist, struct cgroup *cgrp,
 				    struct rblist *new_metric_events,
 				    struct rblist *old_metric_events)
 {
-	unsigned i;
+	unsigned int i;
 
 	for (i = 0; i < rblist__nr_entries(old_metric_events); i++) {
 		struct rb_node *nd;