imsm: properly handle values of sync_completed

imsm: properly handle values of sync_completed

The sync_completed can be set to such values:
- two numbers of processed sectors and total during synchronization,
separated with '/';
- 'none' if synchronization process is stopped;
- 'delayed' if synchronization process is delayed.
Handle value of sync_completed not only as numbers but
also check for 'none' and 'delayed'.

Signed-off-by: Alexey Obitotskiy <aleksey.obitotskiy@intel.com>
Reviewed-by: Pawel Baldysiak <pawel.baldysiak@intel.com>
Signed-off-by: Jes Sorensen <Jes.Sorensen@redhat.com>