core/configs/tools: Report IOMMU association of devices via config file

core/configs/tools: Report IOMMU association of devices via config file

We will need this information for emulating VT-d for the root cell:

Add an iommu field to the PCI device config structure and encode the
unit number in the id field of the IOAPIC's irqchip structure.
The config generator fills the fields according to the DMAR ACPI table.
However, we do not yet understand all exotic forms of Device Scope
structures.

If it turns out that there are PCI devices without any IOMMU
association, refuse to generate a config file - such systems are
unsupported (with the temporary exception of AMD platforms).

Update the h87i config accordingly. QEMU currently only exposes a single
DMAR unit, thus the implicit zero-initialization is fine. As the IOMMU
number is only used in the context of the root cell, ioapic-demo and
pci-demo require no updates as well.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>