LU-2675 obd: remove dead code

LU-2675 obd: remove dead code

Remove unused OBD functions: obdo_to_inode(), is_osp_on_mdt(),
oti_init(), oti_alloc_cookies(), oti_free_cookies(),
obdo_from_iattr(), obdo_from_md(), obd_create_async(), obd_pin(),
obd_unpin(), obd_llog_connect(), obd_pin_observer(),
obd_unpin_observer(), md_is_subdir(), md_readpage(), obdo2fid().

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>
Change-Id: I4a9567798259cfde0cf0ab0ae691daac21e29b9c
Reviewed-on: http://review.whamcloud.com/9784
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Bob Glossman <bob.glossman@intel.com>
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>