[Bugfix] Fix incorrect channel order for idefics3 in edge case (#29881)

Signed-off-by: Isotr0py <mozf@mail2.sysu.edu.cn>
Signed-off-by: Isotr0py <2037008807@qq.com>
Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

vllm/model_executor/models/idefics3.py

@@ -338,6 +338,7 @@ class Idefics3MultiModalProcessor(BaseMultiModalProcessor[Idefics3ProcessingInfo
             prompt_ids = self._apply_hf_processor_tokens_only(prompt_ids)
             return BatchFeature(dict(input_ids=[prompt_ids]), tensor_type="pt")
 
+        mm_kwargs = {"input_data_format": "channels_last", **mm_kwargs}
         processed_outputs = super()._call_hf_processor(
             prompt,
             mm_data,