PCI: Add Downstream Port Containment portdrv service type

Add the Downstream Port Containment (PCIE_PORT_SERVICE_DPC) portdrv service
type, available if the device has the DPC extended capability.

[bhelgaas: split to separate patch, changelog]
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
diff --git a/include/uapi/linux/pci_regs.h b/include/uapi/linux/pci_regs.h
index 1becea8..61e95c1 100644
--- a/include/uapi/linux/pci_regs.h
+++ b/include/uapi/linux/pci_regs.h
@@ -670,7 +670,8 @@
 #define PCI_EXT_CAP_ID_SECPCI	0x19	/* Secondary PCIe Capability */
 #define PCI_EXT_CAP_ID_PMUX	0x1A	/* Protocol Multiplexing */
 #define PCI_EXT_CAP_ID_PASID	0x1B	/* Process Address Space ID */
-#define PCI_EXT_CAP_ID_MAX	PCI_EXT_CAP_ID_PASID
+#define PCI_EXT_CAP_ID_DPC	0x1D	/* Downstream Port Containment */
+#define PCI_EXT_CAP_ID_MAX	PCI_EXT_CAP_ID_DPC
 
 #define PCI_EXT_CAP_DSN_SIZEOF	12
 #define PCI_EXT_CAP_MCAST_ENDPOINT_SIZEOF 40