MTP support DeepSeekV3.2

[ZYang6263]

What this PR does / why we need it?

Currently, MTP does not support the DeepSeekV3.2 model. In this PR, we have enabled this feature.

Does this PR introduce any user-facing change?

How was this patch tested?

• vLLM version: v0.11.0
• vLLM main: vllm-project/vllm@2918c1b

[github-actions]

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[gemini-code-assist]

Code Review

This pull request adds MTP support for the DeepSeekV3.2 model by mapping it to the existing DeepSeekMTP implementation. The change is functionally correct. I have provided one comment regarding code duplication to improve long-term maintainability and prevent potential future bugs.

[gemini-code-assist]

The MTP implementation for DeepseekV32ForCausalLM is identical to that of DeepseekV3ForCausalLM. This creates code duplication. To enhance maintainability and prevent potential bugs should the implementation path change in the future, it would be better to define this shared implementation path as a constant and reuse it for both model architectures.

For example:

DEEPSEEK_MTP_IMPL = ("vllm.model_executor.models.deepseek_mtp", "DeepSeekMTP")

_MTP_MODELS = {
    "DeepseekV3ForCausalLM": DEEPSEEK_MTP_IMPL,
    "DeepseekV32ForCausalLM": DEEPSEEK_MTP_IMPL,
    "Qwen3NextForCausalLM":
    ("vllm_ascend.models.qwen3_next_mtp", "CustomQwen3NextMTP")
}

[whx-sjtu]

LGTM

[github-actions]

This pull request has conflicts, please resolve those before we can evaluate the pull request.