[llvm] [clang] [AArch64] Correctly mark Neoverse N2 as an Armv9.0a core (PR #75055)

[Jonathan Thackray via cfe-commits]

jthackray wrote:

> Looking good. Is there a document to reference in the commit message?

Sure, I can put a link to the Technical Reference Manual

https://github.com/llvm/llvm-project/pull/75055