LU-2275: obdclass: Proper error cleaup for class_newdev

class_newdev did not have a proper cleanup for the case of no more
obd devices and used to leak obdtype reference and some memory
in such a case.
This patch fixes the issue.

Change-Id: I6b683f914f5cbcd21ef414fe470ccc88c39c4deb
Signed-off-by: Oleg Drokin <green@whamcloud.com
Reviewed-on: http://review.whamcloud.com/4460
Reviewed-by: Bob Glossman <bob.glossman@intel.com>
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Bobi Jam <bobijam@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>