[llvm] [AMDGPU] Guard RewriteMFMAFormStage recolor against unsafe def/use (PR #217396)

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xgxanq wrote:

<img width="862" height="593" alt="image" src="https://github.com/user-attachments/assets/e988838f-35c9-4aa3-8e57-29e9f4848672" />
I mean that

https://github.com/llvm/llvm-project/pull/217396