### What this PR does / why we need it?
The optimization solution for non-deepseek select_experts is to replace
gating_topk_softmax with softmax+topk+to, which is optimized from 37us
to 14us on bf16/fp16 of qwen3-235b
- vLLM version: v0.9.2
- vLLM main:
1a4f35e2ea
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Signed-off-by: ttanzhiqiang <389825161@qq.com>