Fix Qwen2AudioForConditionalGeneration.forward() and test_flash_attn_kernels_inference_equivalence (#39503)

* Add missing cache_position argument.

* Pass cache_position to language model.

* Overwrite prepare_inputs_for_generation.

* Set model to half precision for Flash Attention test.

* Cast model to bfloat16.

tests/test_modeling_common.py

@@ -3484,6 +3484,7 @@ class ModelTesterMixin:
             model = model_class(config)
 
             model.to(torch_device)
+            model.to(torch.bfloat16)
             dummy_input = inputs_dict[model.main_input_name][:1]
             if dummy_input.dtype in [torch.float32, torch.float16]:
                 dummy_input = dummy_input.to(torch.bfloat16)