drm/amdgpu: start using graphics object ids from DAL.

[Dave Airlie]

DAL has a concept of storing the graphics object ids in a special
small struct, and adding type safety to them.

I'm starting to contemplate bringing some pieces of DAL into the
mainline modesetting code (like the bios parser for a start),
and I think this is the best first step in that direction.

This series converts connectors, encoders and crtcs id to the
DAL objects. I haven't done PLLs yet they are a bit messier and
I probably need to think about them a bit more.

Also DAL doesn't support any of the DVO/external encoders, I've no idea
if they even exist on DCE8 or newer GPUs, so I've done a separate
patch to drop them.

Dave.