Merge branch 'pci/msi'

- Document sysfs "irq" attribute, which contains either the INTx IRQ (the
  intended behavior) or the first MSI IRQ (historical mistake retained for
  backwards compatibility) (Barry Song)

- Rework "irq" sysfs show function to explicitly fetch first MSI IRQ
  instead of depending on core to put it in dev->irq, to enable future core
  cleanup (Barry Song)

* pci/msi:
  PCI/sysfs: Explicitly show first MSI IRQ for 'irq'
  PCI: Document /sys/bus/pci/devices/.../irq