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 <sudipm.mukherjee@gmail.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20210721150216.64823-2-andriy.shevchenko@linux.intel.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>