LU-2675 llog: remove obd_llog_init() and obd_llod_finish()

LU-2675 llog: remove obd_llog_init() and obd_llod_finish()

Since the OBD methods obd_llog_init() and obd_llod_finish() are only
called from MDC we remove them and just call mdc_llog_init() and
mdc_llog_finish() directly. Also simplify the prototypes the latter
functions according to their uses.

Signed-off-by: John L. Hammond <john.hammond@intel.com>
Change-Id: I56f906eacedaa4e2f90742fb129b4d578751a524
Reviewed-on: http://review.whamcloud.com/11781
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Mike Pershin <mike.pershin@intel.com>
Reviewed-by: Bob Glossman <bob.glossman@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>