[clang] [CMAKE][AMDGPU] fix build failure caused by PR #133619 (PR #133776)

[Farzon Lotfi via cfe-commits]

farzonl wrote:

> I tried to build it locally and I got a series of 'undefined reference' errors. Sorry, I will need to revert my approval. Attn. @jhuber6
> 
> Thanks

Could you provide the failures you were seeing, specific build instructions,  and platform you were doing this on.

https://github.com/llvm/llvm-project/pull/133776