Move isSubRegister() and isSuperRegister to MCRegisterInfo.

These were defined on TargetRegisterInfo, but they don't use any information
that's not available in MCRegisterInfo, so sink them down to be available
at the MC layer.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@170608 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed