USB: EHCI: Don't use NO_IRQ in xilinx ehci driver

Drivers shouldn't use NO_IRQ. This driver is used
by Microblaze and PPC. PPC defines NO_IRQ as 0
and Microblaze has removed it.
Signed-off-by: Michal Simek <monstr@monstr.eu>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
CC: Greg Kroah-Hartman <gregkh@suse.de>
CC: Grant Likely <grant.likely@secretlab.ca>
CC: linux-usb@vger.kernel.org
CC: devicetree-discuss@lists.ozlabs.org

drivers/usb/host/ehci-xilinx-of.c

@@ -183,7 +183,7 @@ static int __devinit ehci_hcd_xilinx_of_probe(struct platform_device *op)
 	}
 
 	irq = irq_of_parse_and_map(dn, 0);
-	if (irq == NO_IRQ) {
+	if (!irq) {
 		printk(KERN_ERR "%s: irq_of_parse_and_map failed\n", __FILE__);
 		rv = -EBUSY;
 		goto err_irq;