tiffperf: use correct conversion factor

tiffperf/tiffperf.c

@@ -75,7 +75,7 @@ print_time (const char *fmt, ImageSize *size, Timer *timer)
     size_t total;
 
     total = size->width * size->height * size->num * 2;
-    printf (fmt, ((double) total) / 1000. / 1000. / timer_get_seconds (timer));
+    printf (fmt, ((double) total) / 1024. / 1024. / timer_get_seconds (timer));
 }
 
 int
@@ -87,7 +87,7 @@ main(int argc, char const* argv[])
         .width = 2048,
         .height = 2048,
         .bits = 16,
-        .num = 20
+        .num = 220
     };
 
     uint16_t *data;