Replace tablegen uses of EVT with MVT. Add isOverloaded() to MVT to facilitate. Remov...

Replace tablegen uses of EVT with MVT. Add isOverloaded() to MVT to facilitate. Remove TGValueTypes.cpp since its unused now (and may have been before).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@200036 91177308-0d34-0410-b5e6-96231b3b80d8