No driver registers for PCIE_PORT_SERVICE_VC, so remove it.

This removes the VC "service" files from /sys/bus/pci_express/devices,
e.g., 0000:07:00.0:pcie108, 0000:08:04.0:pcie208 (all the files that
contained "8" as the last digit of the "pcieXXX" part).  The port driver
created these files for PCIe port devices that have a VC Capability.

Since this reduces PCIE_PORT_DEVICE_MAXSERVICES and moves DPC down into the
spot where VC used to be, the DPC sysfs files will now be named "pcieXX8".
I don't think there's anything useful userspace can do with those files, so
I hope nobody cares about these filenames.

There is no VC driver that calls pcie_port_service_register(), so there
never was a /sys/bus/pci_express/drivers/vc directory.
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>