[llvm] [AMDGPU] Split large raw buffer offsets to SOFFSET where allowed (PR #207821)

[Krzysztof Drewniak via llvm-commits]

krzysz00 wrote:

> "While we're here" generally means "this should really be a separate PR" :)

Yeah, fair, I'll do the PR surgery Soon (tm)

https://github.com/llvm/llvm-project/pull/207821