[llvm] [AMDGPU] Do not use 64-bit literals with VOP3* encodings (PR #156602)

[Janek van Oirschot via llvm-commits]

JanekvO wrote:

Do uses of `GCNSubtarget::has64BitLiterals` also require extra gating? Or is that one already fine, as is?

https://github.com/llvm/llvm-project/pull/156602