This commit is primarily a significant cleanup to the interrupt
allocation code that had gotten a bit jumbled from having to
support per-vq MSIX, shared MSIX, MSI, and legacy style interrupts.
Contains projects/virtio commits:
r246064:
virtio_pci: Rewrite allocation of interrupts
r246065:
virtio_pci: Remove spaces before a tab
r246066:
virtio_pci: Dynamically allocate the virtqueue array
r246304:
virtio_pci: Clean up after failed virtqueue alloc attempt
r246305:
virtio_pci: Move no interrupt check into the PCI interrupt handlers
r246308:
virtio_pci: Remove unused variable
MFC after: 1 month
62a69c4153