[AMDGPU] Support mov dpp with 64 bit operands

We define mov/update dpp intrinsics as overloaded but do not
support i64, which is a practically useful type. Fix the
selection and lowering.

Differential Revision: https://reviews.llvm.org/D68673

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@374910 91177308-0d34-0410-b5e6-96231b3b80d8
7 files changed