ACPI: Never return a value from the PCI device's Interrupt Line field if

  it might be bogus -- return 0 instead.

drivers/acpi/pci_irq.c

@@ -346,10 +346,14 @@ acpi_pci_irq_enable (
 	 */
 	if (!irq) {
 		printk(KERN_WARNING PREFIX "No IRQ known for interrupt pin %c of device %s", ('A' + pin), dev->slot_name);
-		if (dev->irq) 
+		/* Interrupt Line values above 0xF are forbidden */
+		if (dev->irq && dev->irq >= 0xF) {
 			printk(" - using IRQ %d\n", dev->irq);
 			return_VALUE(dev->irq);
 		}
+		else
+			return_VALUE(0);
+ 	}
 
 	dev->irq = irq;