[llvm] [AMDGPU] Rename hasGFX12Enc to hasRestrictedSOffset in BUF definitions. NFC. (PR #83434)

[Joe Nash via llvm-commits]

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

LGTM. 
A refactoring suggestion, could be a separate patch. Make hasRestrictedSOffset a field of MTBUF_Pseudo, MUBUF_Pseudo and MUBUF_AtomicPseudo. let InOperandList = getMUBUFIns<...> as a field in those classes. override hasRestrictedSOffset with an outer let where the instructions are actually defined. This would avoid having to pass hasRestrictedSOffset as a parameter super far through the inheritance chain. Or otherwise pack hasRestrictedSOffset into a struct with other fields?

https://github.com/llvm/llvm-project/pull/83434