[PATCH v3 2/2] PCI/portdrv: Add support for PCIe wake interrupt

[Krishna Chaitanya Chundru <krishna.chundru@xxxxxxxxxxxxxxxx>]

PCIe wake interrupt is needed for bringing back PCIe device state
from D3cold to D0.

Implement new functions, of_pci_setup_wake_irq() and
of_pci_teardown_wake_irq(), to manage wake interrupts for PCI devices
using the Device Tree.