AMDGPU: Refactor isVGPRToSGPRCopy

It should now correctly handle physical registers and make
it easier to identify the other direction.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@250132 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed