[llvm] [AMDGPU] make AMDGPUUniformIntrinsicCombine a function pass (PR #165265)

[Pankaj Dwivedi via llvm-commits]

PankajDwivedi-25 wrote:

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@arsenm @ssahasra 

It does not have many functional changes, only things that were required to make it a function pass are present.

Please spare some time to review it so that I can proceed forward the other patch for enabling it in LLC.

https://github.com/llvm/llvm-project/pull/165265