drm/i915: Call drm helpers when duplicating crtc and plane states

Use the helpers introduced by the commit below to properly initialize
the duplicated states.

commit f5e7840b0c4368f8cdbb055188c2a0eef50c3052
Author: Thierry Reding <treding@nvidia.com>
Date:   Wed Jan 28 14:54:32 2015 +0100

    drm/atomic: Add helpers for state-subclassing drivers

Signed-off-by: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_atomic.c

@@ -250,8 +250,12 @@ intel_crtc_duplicate_state(struct drm_crtc *crtc)
 		crtc_state = kmemdup(intel_crtc->config,
 				     sizeof(*intel_crtc->config), GFP_KERNEL);
 
-	if (crtc_state)
-		crtc_state->base.crtc = crtc;
+	if (!crtc_state)
+		return NULL;
+
+	__drm_atomic_helper_crtc_duplicate_state(crtc, &crtc_state->base);
+
+	crtc_state->base.crtc = crtc;
 
 	return &crtc_state->base;
 }

drivers/gpu/drm/i915/intel_atomic_plane.c

@@ -85,8 +85,8 @@ intel_plane_duplicate_state(struct drm_plane *plane)
 		return NULL;
 
 	state = &intel_state->base;
-	if (state->fb)
-		drm_framebuffer_reference(state->fb);
+
+	__drm_atomic_helper_plane_duplicate_state(plane, state);
 
 	return state;
 }