drm/i915: Do not handle a null plane state.

With the conversion to atomic this cannot happen any more.
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_atomic_plane.c

@@ -76,11 +76,7 @@ intel_plane_duplicate_state(struct drm_plane *plane)
 	struct drm_plane_state *state;
 	struct intel_plane_state *intel_state;
 
-	if (WARN_ON(!plane->state))
-		intel_state = intel_create_plane_state(plane);
-	else
-		intel_state = kmemdup(plane->state, sizeof(*intel_state),
-				      GFP_KERNEL);
+	intel_state = kmemdup(plane->state, sizeof(*intel_state), GFP_KERNEL);
 
 	if (!intel_state)
 		return NULL;