[AMDGPU] drop getIsFP td helper

We already have isFloatType helper, and they are out of sync.
Drop one and merge the type list.

Differential Revision: https://reviews.llvm.org/D69138

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@375175 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed