imsm: Disable checkpoint updating by mdmon for general migration
imsm contains 2 check-pointing mechanism. One (per array) is used for
initialization and rebuild and second (per container) is used for general
migration (reshape). First is controlled by mdmon, second by mdadm.
To avoid conflicts disable mdmon checkpoints updating for general
migration.
Signed-off-by: Adam Kwolek <adam.kwolek@intel.com> Signed-off-by: NeilBrown <neilb@suse.de>