USB: usb gadget, dead config cleanup

Remove some dead CONFIG_ symbols, and document the status of a few others.
The "gadget_chips.h" references are by and large to drivers which exist
but haven't yet been submitted for merging to the main 2.6 tree.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>