LU-2785 osc: remove unused obd methods

LU-2785 osc: remove unused obd methods

Remove the unused methods osc_punch(), osc_sync(), osc_brw(),
osc_enqueue(), osc_cancel(), osc_llog_init(), osc_llog_finish(), and
their supporting functions. Remove the file obd_ost.h, moving all of
the structures defined there to osc_request.c. Remove several orphaned
obd methods.

Signed-off-by: John L. Hammond <john.hammond@intel.com>
Change-Id: I4148547c52625cb7b173f1b835c9e6e47e19e4f6
Reviewed-on: http://review.whamcloud.com/8547
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Jinshan Xiong <jinshan.xiong@intel.com>
Reviewed-by: Lai Siyao <lai.siyao@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>