pc,pci,virtio fixes and cleanups

This includes pc and pci cleanups and enhancements,
and a virtio bugfix for level interrupts.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

# gpg: Signature made Sun 01 Sep 2013 03:15:36 AM CDT using RSA key ID D28D5469
# gpg: Can't check signature: public key not found

# By Michael S. Tsirkin (3) and others
# Via Michael S. Tsirkin
* mst/tags/for_anthony:
  virtio_pci: fix level interrupts with irqfd
  pc: reduce duplication, fix PIIX descriptions
  hw: Clean up bogus default boot order
  pci: add config space access traces
  pc: fix regression for 64 bit PCI memory
  pci: Introduce helper to retrieve a PCI device's DMA address space

Message-id: 1378023590-11109-1-git-send-email-mst@redhat.com
Signed-off-by: Anthony Liguori <anthony@codemonkey.ws>