This removes several controller-specific #define, and
converts to using the config_buf utilities.  Depends
on the patch I submitted yesterday.  Looking simpler!


Simplify "gadget zero" compile-time configuration.

This removes several controller-specific compile-time config options;
the others are about to be autoconfigured.

 - HIGHSPEED replaced by CONFIG_USB_GADGET_DUALSPEED
 - Default to self-powered operation
 - There's no UI for remote wakeup

It also uses the new config_buf utilities, so it's a bit easier to see
what's really going on (this driver implements four configurations).