Fix model_type

The model_type needs to be set to "layoutlm" in order for it to work with the DocumentQA pipeline (and hence the widget).

config.json

@@ -16,7 +16,7 @@
   "layer_norm_eps": 1e-05,
   "max_2d_position_embeddings": 1024,
   "max_position_embeddings": 514,
-  "model_type": "layoutlm-tc",
+  "model_type": "layoutlm",
   "num_attention_heads": 12,
   "num_hidden_layers": 12,
   "pad_token_id": 1,