staging: usbip: convert usbip-host driver to usb_device_driver

This driver was previously an interface driver. Since USB/IP
exports a whole device, not just an interface, it would make
sense to be a device driver.

This patch also modifies the way userspace sees and uses a
shared device:

* the usbip_status file is no longer created for interface 0, but for
the whole device (such as
/sys/devices/pci0000:00/0000:00:01.2/usb1/1-1/usbip_status).
* per interface information, such as interface class or protocol, is
no longer sent/received; only device specific information is
transmitted.
* since the driver was moved one level below in the USB architecture,
there is no need to bind/unbind each interface, just the device as a
whole.

Signed-off-by: Valentina Manea <valentina.manea.m@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/include/linux/usb.h b/include/linux/usb.h
index c716da1..f434619 100644
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -1668,6 +1668,10 @@
 /* this request isn't really synchronous, but it belongs with the others */
 extern int usb_driver_set_configuration(struct usb_device *udev, int config);
 
+/* choose and set configuration for device */
+extern int usb_choose_configuration(struct usb_device *udev);
+extern int usb_set_configuration(struct usb_device *dev, int configuration);
+
 /*
  * timeouts, in milliseconds, used for sending/receiving control messages
  * they typically complete within a few frames (msec) after they're issued