Fix wrong setcc result type when legalizing uaddo/usubo

No test because no in-tree targets change the bitwidth of the
setcc type depending on the bitwidth of the compared type.

Patch by Ke Bai

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@209771 91177308-0d34-0410-b5e6-96231b3b80d8