LU-3534 osp: move RPC pack from declare to execution phase

LU-3534 osp: move RPC pack from declare to execution phase

1. Since we will have full aysnc update support, i.e. do not
need order update anymore, move RPC pack from declare to
execution phase, and these remote updates will be sent during
transaction stop after local transaction is stopped.

2. Add update callback for each update, so after the update request
is done, these callback will be called correspondently for each
update.

3. Remove tu_sent_after_local_trans, because every remote
transaction will be sent after local transaction is finished, in
lod_trans_stop()->osp_trans_stop(). Note: RPC should be sent after
local transaction is stopped, to avoid sending RPC while holding
transaction.

Change-Id: I296e2eaf8b922fe58fe88df074458545f102a69a
Signed-off-by: Wang Di <di.wang@intel.com>
Reviewed-on: http://review.whamcloud.com/10794
Tested-by: Jenkins
Reviewed-by: Alex Zhuravlev <alexey.zhuravlev@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Lai Siyao <lai.siyao@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>