drm: rcar-du: Remove test for impossible error condition

The driver has lost platform data support a long time ago. R-Car DU
devices can only be instantiated through DT now, making it impossible to
have a NULL DT node pointer. Remove the error check.
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Reviewed-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>

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

@@ -294,17 +294,11 @@ static int rcar_du_remove(struct platform_device *pdev)
 
 static int rcar_du_probe(struct platform_device *pdev)
 {
-	struct device_node *np = pdev->dev.of_node;
 	struct rcar_du_device *rcdu;
 	struct drm_device *ddev;
 	struct resource *mem;
 	int ret;
 
-	if (np == NULL) {
-		dev_err(&pdev->dev, "no device tree node\n");
-		return -ENODEV;
-	}
-
 	/* Allocate and initialize the DRM and R-Car device structures. */
 	rcdu = devm_kzalloc(&pdev->dev, sizeof(*rcdu), GFP_KERNEL);
 	if (rcdu == NULL)