[llvm] [AMDGPU] Remove unnecessary predicates from aliases. NFC. (PR #91602)

[Joe Nash via llvm-commits]

Sisyph wrote:

Is this PR related to https://github.com/llvm/llvm-project/pull/89288 ? I think in practice the export pseudo needs HasExportInsts for selection, the Export Real needs isGFX12Plus for lowering to MCInst, and the MnemonicAlias needs isGFX12Plus for having the alias on the right targets

https://github.com/llvm/llvm-project/pull/91602