model: fix colpali for update transformer (#314)

Author: rebel-kblee

src/optimum/rbln/transformers/models/colpali/modeling_colpali.py

@@ -270,7 +270,7 @@ def from_model(
         """
         if not hasattr(model, "vision_tower"):
             model.vision_tower = model.vlm.vision_tower
-            del model.vlm.vision_tower
+            del model.vlm.model.vision_tower
         model = super().from_model(model, config, rbln_config, model_save_dir, subfolder, **kwargs)
         return model