[llvm] [InstCombine] Remove checks for -1 and 0 in saturated unsigned add (NFC) (PR #153047)

[Nikita Popov via llvm-commits]

https://github.com/nikic requested changes to this pull request.

Check that are necessary for correctness cannot be omitted, because canonicality is not guaranteed for non-root instructions.

https://github.com/llvm/llvm-project/pull/153047