PCI: of: Propagate firmware node by calling device_set_node()

Insulate pci_set_of_node() and pci_set_bus_of_node() from possible
changes to fwnode_handle implementation by using device_set_node()
instead of open-coding dev->dev.fwnode assignments.

Link: https://lore.kernel.org/r/20230421100939.68225-1-andriy.shevchenko@linux.intel.com


Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>