PCI/MSI: Use msi_domain_info:: Bus_token

Set the bus token in the msi_domain_info structure and let the core code
handle the update.

Signed-off-by: Ahmed S. Darwish <darwi@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Link: https://lore.kernel.org/r/20221111122014.352437595@linutronix.de