[llvm] [X86] Guard PSADBW reduction combine against non-simple extended types (#227718) (PR #228396)

[Archit Gupta via llvm-commits]

Architag1503 wrote:

@RKSimon Thanks for the review! I have rewritten the PR description to be brief and to the point.

@github-actions I confirm that I have read the LLVM Developer Policy, Code Review Policy, and LLVM AI Tool Use Policy. In accordance with the AI Tool Use Policy, AI tool usage has been noted in the PR description.

https://github.com/llvm/llvm-project/pull/228396