The PCI bus number is usually set by the host during the enumeration.
In the s390 architecture we neither get a Device Tree nor have an
enumeration understanding bridge devices.
Let's fake the enumeration on reset and set the PCI_PRIMARY_BUS,
PCI_SECONDARY_BUS and PCI_SUBORDINATE_BUS config entries for the
bridges.
Let's add the configuration of these three config entries on bridge hot
plug.
The bus number is calculated based on a new entry, bus_num of the
S390pciState device.
This commit is inspired by what spapr pci does.
Signed-off-by: Pierre Morel <pmorel@linux.vnet.ibm.com>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>