drm: rcar-du: error message is not needed for drm_vblank_init()

The only reason drm_vblank_init() could return an error at the
moment is a kcalloc() failure.
So we can remove current error message completely.
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>

drivers/gpu/drm/rcar-du/rcar_du_drv.c

@@ -339,10 +339,8 @@ static int rcar_du_probe(struct platform_device *pdev)
 	 * disabled for all CRTCs.
 	 */
 	ret = drm_vblank_init(ddev, (1 << rcdu->info->num_crtcs) - 1);
-	if (ret < 0) {
-		dev_err(&pdev->dev, "failed to initialize vblank\n");
+	if (ret < 0)
 		goto error;
-	}
 
 	/* DRM/KMS objects */
 	ret = rcar_du_modeset_init(rcdu);