Fixing bug in generation (#11297)

When passing `inputs_embeds` and not `input_ids=None` the generation function fails because `input_ids` is created but the function but it should not.

src/transformers/generation_utils.py

@@ -883,7 +883,7 @@ class GenerationMixin:
         model_kwargs["output_attentions"] = output_attentions
         model_kwargs["output_hidden_states"] = output_hidden_states
 
-        if input_ids is None:
+        if input_ids is None and "inputs_embeds" not in model_kwargs:
             # init `input_ids` with bos_token_id
             input_ids = self._prepare_input_ids_for_generation(bos_token_id, model_kwargs.get("encoder_outputs"))