[Bugfix] Ignore GPTQ quantization of Qwen2-VL visual module

[mgoin]

FIX #9832

This is a workaround for the fact that GPTQ configs generated by AutoGPTQ do not have a list of ignored modules to check if a module should be quantized. We hardcode a case where we set the quant_config = None when passing it to Qwen2-VL's visual module if the config is GPTQ-based.

The issue remains that we will need to use this utility on a case-by-case basis for each model.

Tested with an evaluation:

vllm (pretrained=Qwen/Qwen2-VL-2B-Instruct-GPTQ-Int4), gen_kwargs: (None), limit: None, num_fewshot: 5, batch_size: auto
|Tasks|Version|     Filter     |n-shot|  Metric   |   |Value |   |Stderr|
|-----|------:|----------------|-----:|-----------|---|-----:|---|-----:|
|gsm8k|      3|flexible-extract|     5|exact_match|↑  |0.4481|±  |0.0137|
|     |       |strict-match    |     5|exact_match|↑  |0.4337|±  |0.0137|

As an example see this model https://huggingface.co/Qwen/Qwen2-VL-2B-Instruct-GPTQ-Int4

You can see in its quantization_config that there is no mention of ignored modules:

  "quantization_config": {
    "bits": 4,
    "damp_percent": 0.1,
    "dataset": null,
    "desc_act": false,
    "group_size": 128,
    "modules_in_block_to_quantize": null,
    "quant_method": "gptq",
    "sym": true,
    "true_sequential": true
  },

However looking at the model checkpoint you can see that all of the Linear modules under model.layers.* are quantized, but the Linear modules under visual.blocks.* are not at all:

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[jeejeelee]

I have a question: What should we do if our users execute their own quantization, and they have quantized the visual encoder?