[llvm] [AArch64] Set Olympus cache line size to 64B. (PR #200776)

[Sjoerd Meijer via llvm-commits]

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

This looks good for Olympus, and/or setting the default looks good as well.
Will leave it up to you if you want to set this first, and then think about setting the default. 

https://github.com/llvm/llvm-project/pull/200776