[AMDGPU] Turn AMDGPUUnifyMetadata back into module pass

With the adjustPassManager interface that is now possible to use
custom early module passes.

Differential Revision: https://reviews.llvm.org/D29189

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@293300 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed