[SE] Don't pack raw device mem args

Summary:
Step 4 of getting GlobalDeviceMemory to own its handle.

Take out code to pack untyped device memory types as kernel arguments.
When GlobalDeviceMemory owns its handle, users will never touch untyped
device memory types, so they will never pass them as kernel args.

Reviewers: jlebar

Subscribers: jprice, parallel_libs-commits

Differential Revision: https://reviews.llvm.org/D24177

llvm-svn: 280496