Next batch of atomic work. Most important is the propertification from Rob
and the nth iteration of the actual atomic ioctl originally from Ville.
Big differences compared to earlier revisions:
- Core properties are now fully handled by the core, drivers can only
  handle driver-specific properties.
- Atomic props&ioctl are opt-in per file_priv, userspace needs to
  explicitly ask for it (like universal plane support).
- For now all hidden behind the atomic module option until this has
  settled a bit.
- Atomic modesets are currently not possible since the exact abi for how
  to handle the mode property is still under discussion.

Besides this some cleanup patches from me and the addition of per-object
state to global state backpointers to simplify drivers.

* tag 'topic/atomic-core-2015-01-05' of git://anongit.freedesktop.org/drm-intel:
  drm: Ensure universal_planes is set for atomic
  drm/atomic: Hide drm.ko internal interfaces
  drm: Atomic modeset ioctl
  drm/atomic: atomic connector properties
  drm/atomic: atomic plane properties
  drm: small property creation cleanup
  drm/atomic: atomic_check functions
  drm: add atomic properties
  drm: refactor getproperties/getconnector
  drm: tweak getconnector locking
  drm: add atomic_get_property
  drm: add atomic_set_property wrappers
  drm: get rid of direct property value access
  drm: store property instead of id in obj attachment
  drm: allow property validation for refcnted props
  drm/atomic: Introduce state->obj backpointers
  drm/atomic-helper: Again check modeset *before* plane states
  drm/atomic-helper: Export both plane and modeset check helpers