[clang] [llvm] [AArch64] Make user-visible Arm architecture version strings consistent (PR #98550)

[Jack Styles via cfe-commits]

https://github.com/Stylie777 approved this pull request.

Agree with @tmatheson-arm that there is more standardisation we can do here, but probably out of scope for this PR.

https://github.com/llvm/llvm-project/pull/98550