add _name_or_path

There is a generation error in transformers < 4.42 that will be fixed by having this.

https://github.com/huggingface/transformers/pull/31470

config.json

@@ -1,4 +1,5 @@
 {
+  "_name_or_path": "naver-clova-ix/donut-base",
   "architectures": [
     "VisionEncoderDecoderModel"
   ],