[clang] [CIR][AMDGPU] Add AMDGPU target support to CIR CodeGen (PR #185819)

[David Rivera via cfe-commits]

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

Thanks! Apologies if my PR's were blocking your work - been overwhelmed with school in the last couple of weeks

https://github.com/llvm/llvm-project/pull/185819