Reduntant write bit checks

No point in checking for td_rw(td) || td_write(), since td_write()
will also be true for td_rw().

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/fio.c b/fio.c
index c769445..c39868d 100644
--- a/fio.c
+++ b/fio.c
@@ -641,7 +641,7 @@
 		INIT_LIST_HEAD(&io_u->list);
 
 		io_u->buf = p + max_bs * i;
-		if (td_write(td) || td_rw(td))
+		if (td_write(td))
 			fill_rand_buf(io_u, max_bs);
 
 		io_u->index = i;