LU-6741 osp: bulk transfer for osp_md_read

LU-6741 osp: bulk transfer for osp_md_read

Do buffer bulk read for osp_md_read(), so it would
be more efficient to retrieve update logs from remote
target.

Signed-off-by: wang di <di.wang@intel.com>
Change-Id: Idcb7ef402d02ad46a33cb4d913763235a6215b5b
Reviewed-on: http://review.whamcloud.com/15899
Tested-by: Jenkins
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-by: Lai Siyao <lai.siyao@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>