usb: gadget: goku_udc: add registered flag bit, fixing build

The commit below cleaned up error handling, in part by introducing a
registered flag bit.  This however was not added to the device
structure leding to build failures:

  commit 319feaab
  Author: Dan Carpenter <error27@gmail.com>
  Date:   Tue Oct 5 18:55:34 2010 +0200

    usb: gadget: goku_udc: Fix error path

Add the missing registered flag bit.

Signed-off-by: Andy Whitcroft <apw@canonical.com>
Acked-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>