Revert "[mips][mt][6/7] Add support for mftr, mttr instructions."

This reverts r307836, it broke one of the buildbots. Reverting
while I investigate.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@307939 91177308-0d34-0410-b5e6-96231b3b80d8
15 files changed