[llvm] [X86] lowerShuffleAsLanePermuteAndPermute - ensure we've simplified the demanded shuffle mask elts before testing for a matching shuffle (PR #153554)

[Phoebe Wang via llvm-commits]

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

LGTM.

https://github.com/llvm/llvm-project/pull/153554