[llvm] [AMDGPU] Compiler should synthesize private buffer resource descriptor from flat_scratch_init (PR #79586)

[Scott Linder via llvm-commits]

https://github.com/slinder1 approved this pull request.

Thank you, this LGTM!

We can revisit the wording of the whole section when we no longer request the Private Segment Buffer SGPRs unconditionally

https://github.com/llvm/llvm-project/pull/79586