AMDGPU: Properly handle shader inputs with split arguments

This needs to refer to arguments by their original argument
index, not the argument split index which depends on what
the type splitting decides to do.

Also avoid increment PSInputNum for each split piece.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@337022 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed