perf config: Check not only section->from_system_config but also item's

Currently section->from_system_config is being checked multiple times.
item->from_system_config should be checked instead, when iterating thru
the items in a section. Fix it.

Signed-off-by: Taeung Song <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/builtin-config.c

···
 		fprintf(fp, "[%s]\n", section->name);
 
 		perf_config_items__for_each_entry(&section->items, item) {
-			if (!use_system_config && section->from_system_config)
+			if (!use_system_config && item->from_system_config)
 				continue;
 			if (item->value)
 				fprintf(fp, "\t%s = %s\n",