[llvm] Fix parentheses for clarity in X86ISelLowering.cpp (PR #121954)

[Phoebe Wang via llvm-commits]

phoebewang wrote:

> okay got it. i think i should give it a try again with cloning entirely

Although it's a good practice to learn how to build the entire LLVM, and usually it's necessary for committing a patch, you can sometimes verify the problem without entire build. E.g., https://godbolt.org/z/719WE69ex

https://github.com/llvm/llvm-project/pull/121954