drm/atomic: Do not unset crtc when an encoder is stolen

While we steal the encoder away from the connector the connector may
be updated to use a different encoder.

Without this change if 2 connectors swap encoders one of them will
end up without a crtc.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1452160762-30487-5-git-send-email-maarten.lankhorst@linux.intel.com

drivers/gpu/drm/drm_atomic_helper.c

@@ -134,7 +134,6 @@ steal_encoder(struct drm_atomic_state *state,
 	struct drm_crtc_state *crtc_state;
 	struct drm_connector *connector;
 	struct drm_connector_state *connector_state;
-	int ret;
 
 	/*
 	 * We can only steal an encoder coming from a connector, which means we
@@ -165,9 +164,6 @@ steal_encoder(struct drm_atomic_state *state,
 		if (IS_ERR(connector_state))
 			return PTR_ERR(connector_state);
 
-		ret = drm_atomic_set_crtc_for_connector(connector_state, NULL);
-		if (ret)
-			return ret;
 		connector_state->best_encoder = NULL;
 	}