[llvm] [AArch64] Initial sched model for Neoverse N3 (PR #106371)

[David Green via llvm-commits]

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

If you can make that last change (or explain why it isn't needed), then this LGTM and we can get it in. Thanks

https://github.com/llvm/llvm-project/pull/106371