[llvm] [LegalizeTypes][RISCV] Use SExtOrZExtPromotedOperands to promote operands for USUBSAT. (PR #102781)

[Nikita Popov via llvm-commits]

https://github.com/nikic approved this pull request.

LGTM, proof: https://alive2.llvm.org/ce/z/hJRwjh

Also works for uaddsat if we used straightforward promotion, but not for the umax pattern we currently generate.

https://github.com/llvm/llvm-project/pull/102781