imx-drm: imx-drm-core: get rid of drm_mode_group_init_legacy_group()

Since we're now operating like a conventional DRM driver, doing all
the initialisation within the driver's ->load callback, we don't
need to mess around with the mode groups - we can rely on the one
in the DRM platform code.
Acked-by: Philipp Zabel <p.zabel@pengutronix.de>
Acked-by: Shawn Guo <shawn.guo@linaro.org>
Reviewed-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

drivers/staging/imx-drm/imx-drm-core.c

@@ -274,12 +274,6 @@ static int imx_drm_driver_load(struct drm_device *drm, unsigned long flags)
 
 	drm_kms_helper_poll_init(drm);
 
-	/* setup the grouping for the legacy output */
-	ret = drm_mode_group_init_legacy_group(drm,
-			&drm->primary->mode_group);
-	if (ret)
-		goto err_kms;
-
 	ret = drm_vblank_init(drm, MAX_CRTC);
 	if (ret)
 		goto err_kms;