staging: lustre: obd: remove dead code

Remove unused OBD functions: oti_alloc_cookies(), oti_free_cookies(),
class_observe_import(), class_unobserve_import(),
md_is_subdir(), md_readpage(), obdo2fid(), fid2obdo().

Remove several unused, get-only, and set-only structure members.

Signed-off-by: John L. Hammond <john.hammond@intel.com>
Signed-off-by: James Simmons <uja.ornl@gmail.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-2675
Reviewed-on: http://review.whamcloud.com/9784


Reviewed-by: Bob Glossman <bob.glossman@intel.com>
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Signed-off-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>