[llvm] [X86] Remove unused function createX86PreAMXConfigPass (PR #69547)

[Kazu Hirata via llvm-commits]

kazutakahirata wrote:

> i am WIP on that thing: #69569. lets merge #69569. instead of current pr.

Sounds good.  Thank you for going the extra mile and removing the whole pass!  I'm closing this PR.

https://github.com/llvm/llvm-project/pull/69547