[llvm] [CodeGen] Replace (Min,Max)CSFrameIndex with flag on frame object [NFCI] (PR #170905)

[Sam Elliott via llvm-commits]

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

LGTM. This is a nice cleanup that I think makes most of the code clearer. One Nit which i meant to put into this review but posted as a single comment.

https://github.com/llvm/llvm-project/pull/170905