fix one uncaught deprecation warning for accessing vae_latent_channels in VaeImagePreprocessor (#9372)

deprecation warning vae_latent_channels

Author: haruishi43

src/diffusers/image_processor.py

@@ -569,7 +569,7 @@ def preprocess(
 
             channel = image.shape[1]
             # don't need any preprocess if the image is latents
-            if channel == self.vae_latent_channels:
+            if channel == self.config.vae_latent_channels:
                 return image
 
             height, width = self.get_default_height_width(image, height, width)