LU-7724 mdd: create mdd_changelog_on and _off functions

LU-7724 mdd: create mdd_changelog_on and _off functions

Change mdd_changelog_on with arguments for on and off into
two distinct functions, one for on, one for off

Signed-off-by: Ben Evans <bevans@cray.com>
Change-Id: I42f930fb6a81421c8cd42ebfe95a521007bf5df6
Reviewed-on: http://review.whamcloud.com/18223
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Henri Doreau <henri.doreau@cea.fr>
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>