parport: serial: Retrieve IRQ vector with help of special getter

pci_irq_vector() may be used to retrieve IRQ vector for a PCI device.
Use it instead of direct access.

Acked-by: Sudip Mukherjee <[e-mail]>
Signed-off-by: Andy Shevchenko <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/parport/parport_serial.c

···
                                         "hi" as an offset (see SYBA
                                         def.) */
 		/* TODO: test if sharing interrupts works */
-		irq = dev->irq;
+		irq = pci_irq_vector(dev, 0);
+		if (irq < 0)
+			return irq;
 		if (irq == 0)
 			irq = PARPORT_IRQ_NONE;
 		if (irq == PARPORT_IRQ_NONE) {