### What this PR does / why we need it?
This PR fixes deepseek v3.2 mtp bug.
### Does this PR introduce _any_ user-facing change?
None
### How was this patch tested?
All existed ci tests should pass.
- vLLM version: v0.11.0
- vLLM main:
83f478bb19
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Signed-off-by: whx-sjtu <2952154980@qq.com>