Fixup json bandwidth output

The final version sent in for inclusion had the check mixed
up, so it doesn't output bandwidth unless the calculation
failed.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/stat.c b/stat.c
index 59f3718..38c5d02 100644
--- a/stat.c
+++ b/stat.c
@@ -775,7 +775,7 @@
 	if (ovals)
 		free(ovals);
 
-	if (!calc_lat(&ts->bw_stat[ddir], &min, &max, &mean, &dev)) {
+	if (calc_lat(&ts->bw_stat[ddir], &min, &max, &mean, &dev)) {
 		if (rs->agg[ddir]) {
 			p_of_agg = mean * 100 / (double) rs->agg[ddir];
 			if (p_of_agg > 100.0)