remove useless code

[zzzzwwjj]

What this PR does / why we need it?

vanilla_chunked_prefill_mla and vanilla_decode_mla is unused, so remove it.

Does this PR introduce any user-facing change?

How was this patch tested?

• vLLM version: v0.11.0rc3
• vLLM main: https://github.com/vllm-project/vllm/commit/v0.11.0

[gemini-code-assist]

Code Review

This pull request removes two unused functions, vanilla_chunked_prefill_mla and vanilla_decode_mla, from vllm_ascend/ops/attention.py. Based on the provided files, these functions are indeed not referenced anywhere else in the codebase. This is a good cleanup that improves code maintainability by removing dead code. The change is straightforward and correct.

[github-actions]

👋 Hi! Thank you for contributing to the vLLM Ascend project. The following points will speed up your PR merge:‌‌

• A PR should do only one thing, smaller PRs enable faster reviews.
• Every PR should include unit tests and end-to-end tests ‌to ensure it works and is not broken by other future PRs.
• Write the commit message by fulfilling the PR description to help reviewer and future developers understand.

If CI fails, you can run linting and testing checks locally according Contributing and Testing.