[llvm] [Exegesis][AArch64] Use more generic cycles counter (PR #133376)

[Aiden Grossman via llvm-commits]

https://github.com/boomanaiden154 approved this pull request.

Thanks for the additional info.

This seems reasonable enough to me, but please wait for approval from one of the other reviewers I've pinged as I've only ever worked on the X86 bits of `llvm-exegesis`.

https://github.com/llvm/llvm-project/pull/133376