missing entries from docs/specs/pci-ids.txt ?

[Peter Maydell]

I noticed today that docs/specs/pci-ids.txt doesn't have
an entry for the virtio-iommu, which is defined in pci.h as

#define PCI_DEVICE_ID_VIRTIO_IOMMU       0x1014

There seem to be a few other virtio ID values defined in the
header but not in the txt file too -- do we need to update it?

Conversely, none of the "modern" ID values in the txt file seem
to have a #define. I suspect I'm missing something about how
this works.

thanks
-- PMM