[llvm] [X86] Add AMXProgModel to YAML serialization (PR #94988)

[Phoebe Wang via llvm-commits]

https://github.com/phoebewang approved this pull request.

Looks great! I didn't think of it.

Is it only used for MIR test? Or it has other usage?

https://github.com/llvm/llvm-project/pull/94988