[clang] [Clang] Remove AArch64TargetInfo::setArchFeatures (PR #146107)

[Tomas Matheson via cfe-commits]

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

I'm surprised this has no effect, but if so LGTM. Are any of the values set here now dead?

https://github.com/llvm/llvm-project/pull/146107