Fix a logic error in DwarfExpression::addMachineReg()

This fixes PR34323 and thus splitting undescribable registers into
smaller, describable sub-registers.

https://bugs.llvm.org/show_bug.cgi?id=34323

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@311951 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed