[clang] [llvm] [AArch64] FEAT_SPEv1p2 is optional in v8.7-A and v9.2-A (PR #123336)

[Tomas Matheson via llvm-commits]

https://github.com/tmatheson-arm approved this pull request.

LGTM, assuming no objections to CPU changes.

https://github.com/llvm/llvm-project/pull/123336