fix from_transformer() with extra conditioning channels (#9364)

* fix from_transformer() with extra conditioning channels

* style fix

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Co-authored-by: YiYi Xu <yixu310@gmail.com>
Co-authored-by: Álvaro Somoza <somoza.alvaro@gmail.com>

src/diffusers/models/controlnet_sd3.py

@@ -242,9 +242,12 @@ class SD3ControlNetModel(ModelMixin, ConfigMixin, PeftAdapterMixin, FromOriginal
             module.gradient_checkpointing = value
 
     @classmethod
-    def from_transformer(cls, transformer, num_layers=12, load_weights_from_transformer=True):
+    def from_transformer(
+        cls, transformer, num_layers=12, num_extra_conditioning_channels=1, load_weights_from_transformer=True
+    ):
         config = transformer.config
         config["num_layers"] = num_layers or config.num_layers
+        config["extra_conditioning_channels"] = num_extra_conditioning_channels
         controlnet = cls(**config)
 
         if load_weights_from_transformer: