t/dedupe: fix off-by 1.024 in bandwidth

Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/t/dedupe.c b/t/dedupe.c
index 69ebc8a..b3ab0f9 100644
--- a/t/dedupe.c
+++ b/t/dedupe.c
@@ -361,7 +361,7 @@
 		this_items *= blocksize;
 		tdiff = mtime_since_now(&last_tv);
 		if (tdiff) {
-			this_items /= tdiff;
+			this_items = (this_items * 1000) / (tdiff * 1024);
 			printf("%3.2f%% done (%luKB/sec)\r", perc, this_items);
 			last_nitems = nitems;
 			fio_gettime(&last_tv, NULL);