drm/ttm: moving the LRU into the resource

[Christian König]

Hi guys,

let's hope that I have fixed and documented everything now.

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.

Based on this set I've added an optimization for RADV which Bas pointed
out as valuable.

Please review, test and/or comment,
Christian.