LU-3539 protocol: Change UPDATE_OBJ RPC format

LU-3539 protocol: Change UPDATE_OBJ RPC format

This patch updates struct update for DNE phase II.  See the DNE phase
II HLD for more information.

The comment describing the UPDATE_OBJ RPC format is already a bit out
of date.  This patch simplies and updates it so that the overall
structure is easier to see while the details are commented in-line.

The related type names are modified to be more consistent with the
terminology used in the HLD and the comment.

Change OBJ_XXX-->OUT_XXX, and refine a few update structures to
object_update_xxx. And there are no logic changes in this patch.

Change-Id: I4355b4c863abb448713115f17b80402ec96009f8
Signed-off-by: Di Wang <di.wang@intel.com>
Signed-off-by: Li Wei <wei.g.li@intel.com>
Reviewed-on: http://review.whamcloud.com/7128
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Tested-by: Jenkins
Reviewed-by: Alex Zhuravlev <alexey.zhuravlev@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>