Staging: go7007: small cleanup

small cleanup of go7007:

- prepare for urb->status conversion
- micro optimization
- use kzalloc
- fix free of memory in use in go7007_usb_disconnect

Signed-off-by: Oliver Neukum <oneukum@suse.de>
Cc: Cohen <rcohen@snurgle.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>