[llvm] [X86] Narrow vXi32/vXi64 usubsat to vpsubusb/vpsubusw when LHS is known to fit in fewer bits (PR #206592)

[Simon Pilgrim via llvm-commits]

https://github.com/RKSimon requested changes to this pull request.

Please revert all the clang-format changes you've made to X86ISelLowering.cpp

https://github.com/llvm/llvm-project/pull/206592