[Refactor] Fix Compile Warning #1444-D

[yewentao256]

Purpose

A follow up PR for #21208

Fix Compile Warning 1444-D: type "cub::CUB_200802_SM_1000::Sum" was declared deprecated ("use cuda::std::plus instead")

Now tested on AMD MI300, this version should work.

Test

Using /mnt/nvme5n1p1/wentao/.venv/lib/python3.12/site-packages
Searching for mdurl==0.1.2
Best match: mdurl 0.1.2
Adding mdurl 0.1.2 to easy-install.pth file

Using /mnt/nvme5n1p1/wentao/.venv/lib/python3.12/site-packages
Finished processing dependencies for vllm==0.10.0rc2.dev74+g7c734ee09.d20250723.rocm624
(wentao) wentao@ENC1-CLS01-SVR08:~/vllm$ pip show vllm
Name: vllm
Version: 0.10.0rc2.dev74+g7c734ee09.d20250723.rocm624
Summary: A high-throughput and memory-efficient inference and serving engine for LLMs
Home-page: https://github.com/vllm-project/vllm

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[gemini-code-assist]

Code Review

This pull request addresses a compile-time deprecation warning for cub::Sum on CUDA by replacing it with the recommended cuda::std::plus<float>. The change is well-implemented using a type alias AddOp to handle the platform-specific code for CUDA and ROCm, ensuring that ROCm builds continue to use cub::Sum which is not deprecated on that platform. The changes are correct, targeted, and improve the maintainability of the codebase by resolving the warning. The code modifications are sound, and I have no further feedback.

[yewentao256]

@houseroad CC, thanks~

[mgoin]

This seems safe, thanks