drm/ttm: moving the LRU into the resource

Hi guys,

I've already send out this patch set a couple of times.

This fixes the fundamental problem in TTM that during a move a buffer has resources allocated from two different domains at the same time.

Additional to that it's a prerequisite to remove ghost objects and allow to allocate multiple resources per BO.

I should have fixed all previous review comments as far as I can see, but probably better to take another look.

Regards, Christian.