- Create a pir0 psuedo device as a child of legacy0 if we attach a legacy

- Create a pir0 psuedo device as a child of legacy0 if we attach a legacy
  host-PCI bridge device and find a valid $PIR.
- Make pci_pir_parse() private to pci_pir.c and have pir0's attach routine
  call it instead of having legacy_pcib_attach() call it.
- Implement suspend/resume support for the $PIR by giving pir0 a resume
  method that calls the BIOS to reroute each link that was already routed
  before the machine was suspended.
- Dump the state of the routed flag in the links display code.
- If a link's IRQ is set by a tunable, then force that link to be re-routed
  the first time it is used.
- Move the 'Found $PIR' message under bootverbose as the pir0 description
  line lists the number of entries already.  The pir0 line also only shows
  up if we are actually using the $PIR which is a bonus.
- Use BUS_CONFIG_INTR() to ensure that any IRQs used by a PCI link are
  set to level/low trigger/polarity.