xhci: Rename virt_dev->port to fake_port.

The "port" field in xhci_virt_dev stores the port number associated with
one of the two xHCI split roothubs, not the unique port number the xHCI
hardware uses.  Since we'll need to store the real hardware port number in
future patches, rename this field to "fake_port".

Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>