[llvm] [AMDGPU] AMDGPULateCodeGenPrepare Legacy PM: replace `setPreservesAll()` with `setPreservesCFG()` (PR #148167)

[Nicolai Hähnle via llvm-commits]

https://github.com/nhaehnle commented:

Basically LGTM, but a nit in the comments. (Also, this depends on #148165)

https://github.com/llvm/llvm-project/pull/148167