Problem about processor in load_pretrained_model

Hi Teams,

I'm trying to evaluate VideoLLaMA2 on MVBench. As I run the inference_video_mcqa_mvbench.py, the following traceback occurs:

```
Traceback (most recent call last):
File "/***/VideoLLaMA2/videollama2/eval/inference_video_mcqa_mvbench.py", line 203, in
run_inference(args)
File "/***/VideoLLaMA2/videollama2/eval/inference_video_mcqa_mvbench.py", line 164, in run_inference
for i, line in enumerate(tqdm(val_loader)):
File "/***/python3.11/site-packages/tqdm/std.py", line 1178, in __iter__
for obj in iterable:
File "/***/lib/python3.11/site-packages/torch/utils/data/dataloader.py", line 630, in __next__
data = self._next_data()
^^^^^^^^^^^^^^^^^
File "/***/lib/python3.11/site-packages/torch/utils/data/dataloader.py", line 1345, in _next_data
return self._process_data(data)
^^^^^^^^^^^^^^^^^^^^^^^^
File "/***/lib/python3.11/site-packages/torch/utils/data/dataloader.py", line 1371, in _process_data
data.reraise()
File "/***/lib/python3.11/site-packages/torch/_utils.py", line 694, in reraise
raise exception
AttributeError: Caught AttributeError in DataLoader worker process 0.
Original Traceback (most recent call last):
File "/***/lib/python3.11/site-packages/torch/utils/data/_utils/worker.py", line 308, in _worker_loop
data = fetcher.fetch(index)
^^^^^^^^^^^^^^^^^^^^
File "/***/lib/python3.11/site-packages/torch/utils/data/_utils/fetch.py", line 51, in fetch
data = [self.dataset[idx] for idx in possibly_batched_index]
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/***/lib/python3.11/site-packages/torch/utils/data/_utils/fetch.py", line 51, in
data = [self.dataset[idx] for idx in possibly_batched_index]
~~~~~~~~~~~~^^^^^
File "/***/VideoLLaMA2/videollama2/eval/inference_video_mcqa_mvbench.py", line 50, in __getitem__
torch_imgs = self.processor(video_path, s=bound[0], e=bound[1])
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/***/VideoLLaMA2/./videollama2/mm_utils.py", line 202, in process_video
video = processor.preprocess(images, return_tensors='pt')['pixel_values']
^^^^^^^^^^^^^^^^^^^^
AttributeError: 'NoneType' object has no attribute 'preprocess'
```

I find that the `processor` in
https://github.com/DAMO-NLP-SG/VideoLLaMA2/blob/42bf9fe09656f0a155d96db77178fb74ccc9828d/videollama2/model/__init__.py#L193-L208
is initialized as `None`. For `model_type=mistral` in `config.json` of [VideoLLaMA2-7B](https://huggingface.co/DAMO-NLP-SG/VideoLLaMA2-7B) and [VideoLLaMA2-7B-16F](https://huggingface.co/DAMO-NLP-SG/VideoLLaMA2-7B-16F), the `processor` keeps as None, which may cause the traceback above. Could you please help me address the problem? Thanks!