LU-2675 mdt: add mbo_ prefix to members of struct mdt_body

LU-2675 mdt: add mbo_ prefix to members of struct mdt_body

Rename each member of struct mdt_body, adding the prefix mbo_.

Signed-off-by: John L. Hammond <john.hammond@intel.com>
Change-Id: If229b803a5ccdb27378f6fc44445c1c9bf120d8b
Reviewed-on: http://review.whamcloud.com/10202
Tested-by: Jenkins
Reviewed-by: Bob Glossman <bob.glossman@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Mike Pershin <mike.pershin@intel.com>