Fix dtype mismatch error (#10609)

* fix llama

* fix

* fix code style

* add torch type in model.py

---------

Co-authored-by: arda <arda@arda-arc19.sh.intel.com>

python/llm/src/ipex_llm/transformers/model.py

@@ -295,6 +295,15 @@ class _BaseAutoModelClass:
                     )
                 else:
                     kwargs["torch_dtype"] = torch.float16
+            elif load_in_low_bit == "bf16":
+                if torch_dtype is not None and torch_dtype != torch.bfloat16:
+                    invalidInputError(
+                        False,
+                        f"Please use torch_dtype=torch.bfloat16"
+                        f" when setting load_in_low_bit='bf16'."
+                    )
+                else:
+                    kwargs["torch_dtype"] = torch.bfloat16
             else:
                 kwargs["torch_dtype"] = torch_dtype or "auto"
             # Avoid tensor parallel F.Linear Operations