drm/layerscape: reduce excessive stack usage

The fsl-dcu driver copies a drm_mode_config object to its
stack but then only accesses a single member (dpms_property)
once. The data structure is large enough to trigger a warning
about the amount of kernel stack being used:

drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_rgb.c: In function 'fsl_dcu_drm_connector_create':
drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_rgb.c:182:1: error: the frame size of 1040 bytes is larger than 1024 bytes [-Werror=frame-larger-than=]

This changes the fsl_dcu_drm_connector_create() function to
only access the drm_mode_config by reference, which is also
more efficient.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: 109eee2f ("drm/layerscape: Add Freescale DCU DRM driver")
Signed-off-by: Stefan Agner <stefan@agner.ch>

drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_rgb.c

@@ -142,7 +142,7 @@ int fsl_dcu_drm_connector_create(struct fsl_dcu_drm_device *fsl_dev,
 				 struct drm_encoder *encoder)
 {
 	struct drm_connector *connector = &fsl_dev->connector.base;
-	struct drm_mode_config mode_config = fsl_dev->drm->mode_config;
+	struct drm_mode_config *mode_config = &fsl_dev->drm->mode_config;
 	struct device_node *panel_node;
 	int ret;
 
@@ -164,7 +164,7 @@ int fsl_dcu_drm_connector_create(struct fsl_dcu_drm_device *fsl_dev,
 		goto err_sysfs;
 
 	drm_object_property_set_value(&connector->base,
-				      mode_config.dpms_property,
+				      mode_config->dpms_property,
 				      DRM_MODE_DPMS_OFF);
 
 	panel_node = of_parse_phandle(fsl_dev->np, "fsl,panel", 0);