perf test: Reset shadow counts before loading

Otherwise load counting is an average. Without this change
duration_time in test_memory_bandwidth will alter its value if an
earlier test contains duration_time.

This patch fixes an issue that's introduced in the proposed patch:
https://lore.kernel.org/lkml/[e-mail]/
in perf test "Parse and process metrics".

Signed-off-by: Ian Rogers <[e-mail]>
Acked-by: Jiri Olsa <[e-mail]>
Cc: Alexander Shishkin <[e-mail]>
Cc: Andi Kleen <[e-mail]>
Cc: John Garry <[e-mail]>
Cc: Kajol Jain <[e-mail]>
Cc: Kan Liang <[e-mail]>
Cc: Mark Rutland <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Paul Clarke <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Stephane Eranian <[e-mail]>
Link: http://lore.kernel.org/lkml/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/tests/parse-metric.c

···
 	struct evsel *evsel;
 	u64 count;
 
+	perf_stat__reset_shadow_stats();
 	evlist__for_each_entry(evlist, evsel) {
 		count = find_value(evsel->name, vals);
 		perf_stat__update_shadow_stats(evsel, count, 0, st);