Heavily based upon Rob Clark's atomic series.
- Dropped the connector state from the crtc state, instead opting for a
  full-blown connector state. The only thing it has is the desired
  crtc, but drivers which have connector properties have now a
  data-structure to subclass.

- Rename create_state to duplicate_state. Especially for legacy ioctls
  we want updates on top of existing state, so we need a way to get at
  the current state. We need to be careful to clear the backpointers
  to the global state correctly though.

- Drop property values. Drivers with properties simply need to
  subclass the datastructures and track the decoded values in there. I
  also think that common properties (like rotation) should be decoded
  and stored in the core structures.

- Create a new set of ->atomic_set_prop functions, for smoother
  transitions from legacy to atomic operations.

- Pass the ->atomic_set_prop ioctl the right structure to avoid
  chasing pointers in drivers.

- Drop temporary boolean state for now until we resurrect them with
  the helper functions.

- Drop invert_dimensions. For now we don't need any checking since
  that's done by the higher-level legacy ioctls. But even then we
  should also add rotation/flip tracking to the core drm_crtc_state,
  not just whether the dimensions are inverted.

- Track crtc state with an enable/disable. That's equivalent to
  mode_valid, but a bit clearer that it means the entire crtc.

The global interface will follow in subsequent patches.

v2: We need to allow drivers to somehow set up the initial state and
clear it on resume. So add a plane->reset callback for that. Helpers
will be provided with default behaviour for all these.

v3: Split out the plane->reset into a separate patch.

v4: Improve kerneldoc in drm_crtc.h

v5: Remove unused inline functions for handling state objects, those
callbacks are now mandatory for full atomic support.

v6: Fix commit message nit Sean noticed.
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>