io_uring: finish IOU_OK -> IOU_COMPLETE transition

IOU_COMPLETE is more descriptive, in that it explicitly says that the
return value means "please post a completion for this request". This
patch completes the transition from IOU_OK to IOU_COMPLETE, replacing
existing IOU_OK users.

This is a purely mechanical change.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

io_uring/statx.c

@@ -59,7 +59,7 @@ int io_statx(struct io_kiocb *req, unsigned int issue_flags)
 
 	ret = do_statx(sx->dfd, sx->filename, sx->flags, sx->mask, sx->buffer);
 	io_req_set_res(req, ret, 0);
-	return IOU_OK;
+	return IOU_COMPLETE;
 }
 
 void io_statx_cleanup(struct io_kiocb *req)