fix loss normalization for ddp training

haoneng.lhn

2023-12-08 ace42e5043be992c3a324fc637ba0594f10ad3b6

 egs/aishell/transformer/utils/prepare_checkpoint.py

@@ -16,3 +16,4 @@
    except BaseException:
        raise BaseException(f"Please download pretrain model from ModelScope firstly.")
    shutil.copy(os.path.join(checkpoint_dir, checkpoint_name), os.path.join(pretrained_model_path, "model.pb"))
    shutil.copy(os.path.join(checkpoint_dir, "config.yaml"), os.path.join(pretrained_model_path, "config.yaml"))