[llvm] [BOLT] Simplify RAState helpers (NFCI) (PR #162820)

[Gergely Bálint via llvm-commits]

bgergely0 wrote:

I've found a bug that I accidentally fixed in the next PR in the stack, and not here 🤦 . Now this should be fixed. 
(Luckily the [large-bolt-tests repo](https://github.com/arm/large-bolt-tests) caught it)

https://github.com/llvm/llvm-project/pull/162820