drm/i915: clean up atomic plane check functions, v2.

By passing crtc_state to the check_plane functions a lot of duplicated
code can be removed. There are still some transitional helper calls,
they will be removed later.

Changes since v1:
- Revert state->visible changes.
- Use plane->state->crtc instead of plane->crtc.
- Use drm_atomic_get_existing_crtc_state.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Tested-by(IVB): Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 198cb20..0145e08 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -613,6 +613,7 @@
 	void (*disable_plane)(struct drm_plane *plane,
 			      struct drm_crtc *crtc, bool force);
 	int (*check_plane)(struct drm_plane *plane,
+			   struct intel_crtc_state *crtc_state,
 			   struct intel_plane_state *state);
 	void (*commit_plane)(struct drm_plane *plane,
 			     struct intel_plane_state *state);