irqchip/xilinx: Fill error code when irq domain registration fails

There is no ret filled in case of irq_domain_add_linear() failure.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Stefan Asserhall <stefan.asserhall@xilinx.com>
Link: https://lore.kernel.org/r/20200317125600.15913-3-mubin.usman.sayyed@xilinx.com

drivers/irqchip/irq-xilinx-intc.c

@@ -228,6 +228,7 @@ static int __init xilinx_intc_of_init(struct device_node *intc,
 						  &xintc_irq_domain_ops, irqc);
 	if (!irqc->root_domain) {
 		pr_err("irq-xilinx: Unable to create IRQ domain\n");
+		ret = -EINVAL;
 		goto error;
 	}