[clang] Revert "[Clang] Set default LTO mode for AMDGCN/SPIR-V targets to full" (PR #202714)

[Krzysztof Parzyszek via cfe-commits]

kparzysz wrote:

> From what I can tell you change a `.bc` to a `.s`, both will unblock PRs.

I'm not seeing any pull requests with the fix.

https://github.com/llvm/llvm-project/pull/202714