[llvm] [LV] Simplify the chain traversal in `getScaledReductions()` (NFCI) (PR #184830)

[Gaëtan Bossu via llvm-commits]

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

LGTM! I still don't understand that code entirely, but you made it a lot easier to process!

https://github.com/llvm/llvm-project/pull/184830