Have getCalleeSavedRegs take a non-null MachineFunction all the

Have getCalleeSavedRegs take a non-null MachineFunction all the
time. The target independent code was passing in one all the
time and targets weren't checking validity before using. Update
a few calls to pass in a MachineFunction where necessary.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231970 91177308-0d34-0410-b5e6-96231b3b80d8