memory: omap-gpmc: add error message if bank-width property is absent

Instead of failing silently log a hint for the dt author about the
reason of the failure.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Roger Quadros <rogerq@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

drivers/memory/omap-gpmc.c

@@ -2083,8 +2083,11 @@ static int gpmc_probe_generic_child(struct platform_device *pdev,
 	} else {
 		ret = of_property_read_u32(child, "bank-width",
 					   &gpmc_s.device_width);
-		if (ret < 0)
+		if (ret < 0) {
+			dev_err(&pdev->dev, "%s has no 'bank-width' property\n",
+				child->full_name);
 			goto err;
+		}
 	}
 
 	/* Reserve wait pin if it is required and valid */