[llvm] [DAGCombine] Correctly extend the constant RHS in `TargetLowering::SimplifySetCC` (PR #152862)

[via llvm-commits]

AZero13 wrote:

https://github.com/dtcxzyw/llvm-codegen-benchmark/commit/42b12a853669741a171a9c73c23402fce96882c2

@dtcxzyw This code change did in fact affect codegen of some files in codegen benchmark. Considering this is a miscompile, can we backport this?

https://github.com/llvm/llvm-project/pull/152862