[llvm] [AMDGPU] Add amdgpu-lower-special-lds pass to lower named-barrier LDS (PR #165692)

[Pierre van Houtryve via llvm-commits]

https://github.com/Pierre-vh commented:

I don't see the changes that remove the logic from LowerModuleLDS? Are they missing?

https://github.com/llvm/llvm-project/pull/165692