staging: wilc1000: avoid request_irq() if interrupt is invalid

Do not request irq if the irq number wasn't passed from device tree
or it was wrongly passed.

Fixes: 57041706005ea ("staging: wilc1000: copy driver from github")
Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>

Author: claudiubeznea

drivers/staging/wilc1000/netdev.c

@@ -182,7 +182,8 @@ static int init_irq(struct net_device *dev)
 			return -EINVAL;
 		}
 	} else {
-		if (request_irq(wl->dev_irq_num, host_wakeup_isr,
+		if (wl->dev_irq_num &&
+		    request_irq(wl->dev_irq_num, host_wakeup_isr,
 					     IRQF_TRIGGER_FALLING |
 					     IRQF_NO_SUSPEND,
 					     "WILC_IRQ", wl) < 0) {