- Hook up the default implementations of the MSI/MSI-X pcib_if methods

- Hook up the default implementations of the MSI/MSI-X pcib_if methods
  so requests may bubble up to a host-PCI bridge driver.
- Distinguish between PCI and PCIe bridges in the device description
  so it's a bit easier to follow what hangs off of what in the dmesg.
  Unfortunately we can't also tell PCI and PCI-X apart based on the
  information provided in the OFW device tree.
- Add quirk handling for the ALi M5249 found in Fire-based machines
  which are used as a PCIe-PCIe bridge there. These are obviously
  subtractive decoding as as they have a PCI-ISA bridge on their
  secondary side (and likewise don't include the ISA I/O range in
  their bridge decode) but don't indicate this via the class code.
  Given that this quirk isn't likely to apply to all ALi M5249 and
  I have no datasheet for these chips so I could implement a check
  using the chip specific bits enabling subtractive decoding this
  quirk handling is added to the MD code rather than the MI one.

git-svn-id: svn://svn.freebsd.org/base/stable/8@202377 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f