A couple of bugs in netdev_unregister_sysfs; still working on the harder
refcount issues.
- if driver sets get_stats after register then unregister 
  will attempt to delete kobject that has not be initialized.
- unregister should call kobject_unregister not kobject_del.

cleanup's:
- use strlcpy instead of snprintf
- don't need to memset the stats kobject