[llvm] [DirectX] Preserve value names in DXILOpLowering. NFC (PR #108089)

[Cooper Partin via llvm-commits]

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

Yep.. names looked preserved.  So the CHECK: tests are looking for anything now when before they looked for any number?

https://github.com/llvm/llvm-project/pull/108089