Both pcie-to-pci-bridge and dmi-to-pci-bridge can be used to
create a traditional PCI topology in a pure PCIe guest such as
those using the x86_64/q35 or aarch64/virt machine type;
however, the former should be preferred, as it doesn't need to
obey limitation of real hardware and is completely
architecture-agnostic.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1520821Signed-off-by: NAndrea Bolognani <abologna@redhat.com>
Reviewed-by: NJohn Ferlan <jferlan@redhat.com>