TailDuplication: Save MF and reduce number of parameters. NFC

Save the function in the class, and then don't pass it around. This reduces the
number of parameters and makes calls to member functions simpler.
No Functional Change.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@279700 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed