pci: Allocate PCIe host bridge PCI ID

We are going to introduce a PCIe host controller that doesn't exist that
way in real hardware, but still needs to expose some PCIe root device which
has PCI IDs.

Allocate a PCI ID in the Red Hat space that we use for other devices of this
kind.

Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

include/hw/pci/pci.h

@@ -89,6 +89,7 @@
 #define PCI_DEVICE_ID_REDHAT_SERIAL4     0x0004
 #define PCI_DEVICE_ID_REDHAT_TEST        0x0005
 #define PCI_DEVICE_ID_REDHAT_SDHCI       0x0007
+#define PCI_DEVICE_ID_REDHAT_PCIE_HOST   0x0008
 #define PCI_DEVICE_ID_REDHAT_QXL         0x0100
 
 #define FMT_PCIBUS                      PRIx64