Revert "mdadm: remove container_enough logic"

Revert "mdadm: remove container_enough logic"

Mentioned patch changes way of IMSM member arrays assembling, they are
updated by every new drive incremental processes. Previously, member
arrays were created and filled once, by last drive incremental process.

We determined regressions with various impact. Unfortunately, initial
testing didn't show them.

Regressions are connected to drive appearance order and may not be
reproducible on every configuration, there are at least two know
issues for now:

- sysfs attributes are filled using old metadata if there is
  outdated drive and it is enumerated first.

- rebuild may be aborted and started from beginning after reboot,
  if drive under rebuild is enumerated as the last one.

This reverts commit 4dde420fc3e24077ab926f79674eaae1b71de10b. It fixes
checkpatch issues and reworks logic to remove empty "if" branch in
Incremental.

Signed-off-by: Mariusz Tkaczyk <mariusz.tkaczyk@linux.intel.com>