drm: qxl: Atomic phase 1: convert cursor to universal plane

In preparation for atomic conversion, let's use the transitional atomic
helpers drm_plane_helper_update/disable.
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/20170227204328.18761-6-krisman@collabora.co.ukSigned-off-by: Gerd Hoffmann <kraxel@redhat.com>

drivers/gpu/drm/qxl/qxl_drv.h

@@ -134,11 +134,6 @@ struct qxl_bo_list {
 struct qxl_crtc {
 	struct drm_crtc base;
 	int index;
-	int cur_x;
-	int cur_y;
-	int hot_spot_x;
-	int hot_spot_y;
-	struct qxl_bo *cursor_bo;
 };
 
 struct qxl_output {