[clang] clang/HIP: Remove __ockl_fdot2 declaration (PR #201878)

[Kewen Meng via cfe-commits]

Kewen12 wrote:

> > > https://lab.llvm.org/buildbot/#/builders/232/builds/1544
> > 
> > 
> > This has long out of date HIP headers
> 
> Specifically this needs [ROCm/rocm-systems#2230](https://github.com/ROCm/rocm-systems/pull/2230)

Are these headers part of rocm-hip-runtime? The bot runs on 7.1.1 (https://github.com/ROCm/aomp/blob/aomp-dev/upstream-buildbots/manylinux-hip-tpl/Dockerfile#L19) 

I m trying to figure out what to update.

https://github.com/llvm/llvm-project/pull/201878