[deepseek] kernel block size for UniformTypeKVCacheSpecs

[heheda12345]

Purpose

After #24486 , deepseek 3.2 will throw this error:

 NotImplementedError: unknown kv cache spec UniformTypeKVCacheSpecs

This PR fix it.

FIX #26524

Test Plan

python3 examples/offline_inference/basic/generate.py --model deepseek-ai/DeepSeek-V3.2-Exp --gpu_memory_utilization 0.8 -tp 8

Test Result

--------------------------------------------------
Prompt: 'Hello, my name is'
Generated text: ' Christian Munoz and\nthis is my final project for my summer\n2020'
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Prompt: 'The president of the United States is'
Generated text: ' the head of state and head of government of the United States, indirectly elected to'
--------------------------------------------------
Prompt: 'The capital of France is'
Generated text: ' Paris, and the capital of Spain is Madrid.\n\n**Question:** The capital of'
--------------------------------------------------
Prompt: 'The future of AI is'
Generated text: ' the future of work\n\nThe future of AI is the future of work\n\nThe'
--------------------------------------------------

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Essential Elements of an Effective PR Description Checklist

• The purpose of the PR, such as "Fix some issue (link existing issues this PR will resolve)".
• The test plan, such as providing test command.
• The test results, such as pasting the results comparison before and after, or e2e results
• (Optional) The necessary documentation update, such as updating supported_models.md and examples for a new model.
• (Optional) Release notes update. If your change is user facing, please update the release notes draft in the Google Doc.

[gemini-code-assist]

Code Review

This pull request correctly adds support for UniformTypeKVCacheSpecs to address an issue with deepseek models. The approach of unpacking the spec and then handling it in the existing logic is sound. I've identified a minor improvement opportunity in the error reporting within gpu_model_runner.py to enhance debuggability for future unhandled spec types.

[LucasWilkinson]

LGTM; thanks for fixing!