bcmgenet: add WOL IRQ check

The driver neglects to check the result of platform_get_irq_optional()'s
call and blithely passes the negative error codes to devm_request_irq()
(which takes *unsigned* IRQ #), causing it to fail with -EINVAL.
Stop calling devm_request_irq() with the invalid IRQ #s.

Fixes: 8562056f ("net: bcmgenet: request Wake-on-LAN interrupt")
Signed-off-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/genet/bcmgenet.c

@@ -4020,10 +4020,12 @@ static int bcmgenet_probe(struct platform_device *pdev)
 
 	/* Request the WOL interrupt and advertise suspend if available */
 	priv->wol_irq_disabled = true;
-	err = devm_request_irq(&pdev->dev, priv->wol_irq, bcmgenet_wol_isr, 0,
-			       dev->name, priv);
+	if (priv->wol_irq > 0) {
+		err = devm_request_irq(&pdev->dev, priv->wol_irq,
+				       bcmgenet_wol_isr, 0, dev->name, priv);
 		if (!err)
 			device_set_wakeup_capable(&pdev->dev, 1);
+	}
 
 	/* Set the needed headroom to account for any possible
 	 * features enabling/disabling at runtime