drm: Set non-desktop property to true for writeback and virtual connectors

The non-desktop property "Indicates the output should be ignored for
purposes of displaying a standard desktop environment or console."

That sounds like it should be true for all writeback and virtual
connectors as you shouldn't render a desktop to them, so set it
by default.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>

Author: 6by9

drivers/gpu/drm/drm_connector.c

@@ -307,7 +307,8 @@ static int drm_connector_init_only(struct drm_device *dev,
 
 	drm_object_attach_property(&connector->base,
 				   config->non_desktop_property,
-				   0);
+				   (connector_type != DRM_MODE_CONNECTOR_VIRTUAL &&
+				   connector_type != DRM_MODE_CONNECTOR_WRITEBACK) ? 0 : 1);
 	drm_object_attach_property(&connector->base,
 				   config->tile_property,
 				   0);