[llvm] [NFC] Partial reduce test to demonstrate regression post commit #cc9c64d (PR #162681)

[Sushant Gokhale via llvm-commits]

sushgokh wrote:

@david-arm in the changed  test, the attribute has "cpu" field instead of "target-cpu". I believe latter one should be correct because both are yielding different IR and codegen. I hope its fine if I change it to "target-cpu"  to avoid one more PR just for this.

https://github.com/llvm/llvm-project/pull/162681