[llvm] [PowerPC] Mask constant operands in ValueBit tracking (PR #67653)

[via llvm-commits]

llvmbot wrote:

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>> Thank you @bzEq for the quick response. Would it be possible to backport this into 18?
>
>/cherry-pick 292d9e8

Error: Command failed due to missing milestone.

https://github.com/llvm/llvm-project/pull/67653