gettime: fix CPU calibration reported mean

Bug introduced in fa80feae. It only affected the reported mean
if --debug=time was used, cosmetic issue.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/gettime.c b/gettime.c
index a60b35f..df42c29 100644
--- a/gettime.c
+++ b/gettime.c
@@ -242,7 +242,7 @@
 	}
 
 	S /= (double) NR_TIME_ITERS;
-	mean /= (double) NR_TIME_ITERS;
+	mean /= 10.0;
 
 	for (i = 0; i < NR_TIME_ITERS; i++)
 		dprint(FD_TIME, "cycles[%d]=%lu\n", i, cycles[i] / 10);