[clang] [NFC][SemaHLSL] Remove check dependent on non-deterministic order (PR #148649)

[Finn Plummer via cfe-commits]

inbelic wrote:

@guy-david  @bevin-hansson This resolved the build issue for me locally when using `DLLVM_ENABLE_EXSTENSIVE_CHECKS`, can you confirm this resolves the issue for you as well?

https://github.com/llvm/llvm-project/pull/148649