[PATCH] usbtest: mo'betta devices, control tests

This updates the usbtest driver:

- Supports more devices for the basic i/o tests,
   using full speed ez-usb firmware (and usbtest
   tweaks!) provided by Martin Diehl.

- Adds another test case, which issues control
   messages to devices.  There will be further
   updates in this area (control queueing, and
   likely improving usbcore api coverage).

- Adds a "generic device" mode where vendor
   (and optionally product) ids can be given as
   module parameters.  Those devices can be used
   for testing control traffic.