Fix warning in UNetMotionModel (#8756)

* update

* Update src/diffusers/models/unets/unet_motion_model.py
Co-authored-by: YiYi Xu <yixu310@gmail.com>

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Co-authored-by: YiYi Xu <yixu310@gmail.com>

src/diffusers/models/unets/unet_motion_model.py

@@ -597,7 +597,9 @@ class UNetMotionModel(ModelMixin, ConfigMixin, UNet2DConditionLoadersMixin):
         if not config.get("num_attention_heads"):
             config["num_attention_heads"] = config["attention_head_dim"]
 
-        config = FrozenDict(config)
+        expected_kwargs, optional_kwargs = cls._get_signature_keys(cls)
+        config = FrozenDict({k: config.get(k) for k in config if k in expected_kwargs or k in optional_kwargs})
+        config["_class_name"] = cls.__name__
         model = cls.from_config(config)
 
         if not load_weights: