This adds some code that gadget drivers can call from
driver initialization, to simplify the "configure against
this hardware" step.


Add endpoint autoconfiguration for gadget drivers.

Endpoint selection is currently being done with conditional compilation.
That doesn't look nice, but more importantly it doesn't work well with
the model that some distributions won't be custom-matched to hardware.
Say, a PDA distro running on iPaq (pxa2xx_udc) or Axim (mq11xx_udc).

This code just makes it easier for drivers to match to hardware at
run-time.  It's a convenience function for something they could have
been doing already, but weren't.