[llvm] [AMDGPU] Do not generate V_FMAC_DX9_ZERO_F32 on GFX12 (PR #171116)

[Florian Mayer via llvm-commits]

fmayer wrote:

> Hi, can you take a look at https://lab.llvm.org/buildbot/#/builders/51/builds/28255?
> 
> I think the PR broke the sanitizer buildbot?
> 
> FYI @fmayer

No this has nothing to do with this PR. This is an infra problem I am trying to address.

https://github.com/llvm/llvm-project/pull/171116