[llvm] [DirectX][NFC] Use LLVM Types in DXIL Operation specifications in DXIL.td (PR #81692)

[S. Bharadwaj Yadavalli via llvm-commits]

bharadwajy wrote:

Updated PR with a change that deletes `DXILType` abstraction and uses LLVM Types.

https://github.com/llvm/llvm-project/pull/81692