[llvm] [ARM][AArch64] Reformat target parser. NFC (PR #82601)

[Jonathan Thackray via llvm-commits]

jthackray wrote:

We've branched our latest release a couple of weeks ago, but are still doing occasional cherry-picks (and I've got pending upstream updates). Would prefer if we could leave until Monday; I'm still catching up as I've been away earlier this week due to half-term holidays.

But yes, it's a good idea to tidy this area of the code up :)

https://github.com/llvm/llvm-project/pull/82601