When configured to pass through a specific host port (using hostbus and
hostport properties), try to claim the port if supported by the kernel.
That will avoid any kernel drivers binding to devices plugged into that
port.  It will not stop any userspace apps (such as usb_modeswitch)
access the device via usbfs though.
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>