irqchip/xilinx: Try to fall back if xlnx,kind-of-intr not provided

The powerpc dts file does not have the xlnx,kind-of-intr property.
Instead of erroring out, give a warning instead. And attempt to
continue to probe the interrupt controller while assuming
kind-of-intr is 0x0 as a fall back.

Acked-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Zubair Lutfullah Kakakhel <Zubair.Kakakhel@imgtec.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

drivers/irqchip/irq-xilinx-intc.c

@@ -179,8 +179,8 @@ static int __init xilinx_intc_of_init(struct device_node *intc,
 
 	ret = of_property_read_u32(intc, "xlnx,kind-of-intr", &irqc->intr_mask);
 	if (ret < 0) {
-		pr_err("irq-xilinx: unable to read xlnx,kind-of-intr\n");
-		goto err_alloc;
+		pr_warn("irq-xilinx: unable to read xlnx,kind-of-intr\n");
+		irqc->intr_mask = 0;
 	}
 
 	if (irqc->intr_mask >> nr_irq)