perf hists: Use struct perf_hpp_fmt::idx in perf_hpp__reset_width

We are going to add dynamic hpp format fields, so we need to make the
'len' change for the format itself, not in the perf_hpp__format
template.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1453109064-1026-5-git-send-email-jolsa@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/ui/hist.c

@@ -629,20 +629,12 @@ unsigned int hists__sort_list_width(struct hists *hists)
 
 void perf_hpp__reset_width(struct perf_hpp_fmt *fmt, struct hists *hists)
 {
-	int idx;
-
 	if (perf_hpp__is_sort_entry(fmt))
 		return perf_hpp__reset_sort_width(fmt, hists);
 
-	for (idx = 0; idx < PERF_HPP__MAX_INDEX; idx++) {
-		if (fmt == &perf_hpp__format[idx])
-			break;
-	}
-
-	if (idx == PERF_HPP__MAX_INDEX)
-		return;
+	BUG_ON(fmt->idx >= PERF_HPP__MAX_INDEX);
 
-	switch (idx) {
+	switch (fmt->idx) {
 	case PERF_HPP__OVERHEAD:
 	case PERF_HPP__OVERHEAD_SYS:
 	case PERF_HPP__OVERHEAD_US: