### What this PR does / why we need it?
Fixes an accuracy bug of Qwen3-next-MTP when batched inferring.
It is descibed in
https://github.com/vllm-project/vllm-ascend/issues/4930.
- vLLM version: v0.12.0
- vLLM main:
ad32e3e19c
Signed-off-by: drslark <slarksblood@qq.com>