LU-3534 osp: transfer updates with bulk RPC

LU-3534 osp: transfer updates with bulk RPC

Send update request with bulk RPC(iovec), and update request
will be split into multiple buffers, so OSP does not need to
allocate big contingous buffer to store the update request.

Signed-off-by: wang di <di.wang@intel.com>
Change-Id: I70995a552ee6fdd77f4c0a84d2435e5963e4fd6d
Reviewed-on: http://review.whamcloud.com/13786
Tested-by: Jenkins
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-by: Alex Zhuravlev <alexey.zhuravlev@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>