mdadm: remove container_enough logic

mdadm: remove container_enough logic

Arrays without enough disk count will be assembled but not
started.
Now RAIDs will be assembled always (even if they are failed).
RAID devices in all states will be assembled and exposed
to mdstat.
This change affects only IMSM (for ddf it wasn't used,
container_enough was set to true always).
Removed this logic from incremental_container as well with
runstop checking because runstop condition is being verified
in assemble_container_content function.

Signed-off-by: Pawel Piatkowski <pawel.piatkowski@intel.com>
Signed-off-by: Jes Sorensen <jes@trained-monkey.org>