[llvm] [X86] Disable the `vpdpwssd -> vpmaddwd + vpaddd` combiner pattern on AMD Zen4 (PR #84347)

[Benoit Jacob via llvm-commits]

bjacob wrote:

I see. I'm curious what "address this for the general case in https://github.com/llvm/llvm-project/issues/84182" would look like. Certainly if this actually comes down to a znver4 scheduling model inaccuracy, it would be great to simply fix that, but at the moment I can't find an inaccuracy there that would be relevant to this particular issue.

I've just connected with @ganeshgit on this so I might just be able to bow out of this and let the experts weigh in :-D  Closing this PR for now.

https://github.com/llvm/llvm-project/pull/84347