input: xilinx_ps2: Don't use NO_IRQ

Drivers shouldn't use NO_IRQ. Microblaze and PPC
define NO_IRQ as 0 and this reference will be removed
in near future.

Signed-off-by: Michal Simek <monstr@monstr.eu>
Reviewed-by: Ryan Mallon <rmallon@gmail.com>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
CC: Rob Herring <rob.herring@calxeda.com>

drivers/input/serio/xilinx_ps2.c

@@ -253,7 +253,7 @@ static int __devinit xps2_of_probe(struct platform_device *ofdev)
 	}
 
 	/* Get IRQ for the device */
-	if (of_irq_to_resource(ofdev->dev.of_node, 0, &r_irq) == NO_IRQ) {
+	if (!of_irq_to_resource(ofdev->dev.of_node, 0, &r_irq)) {
 		dev_err(dev, "no IRQ found\n");
 		return -ENODEV;
 	}