FIX: Array after takeover has to be frozen

FIX: Array after takeover has to be frozen

Problem occurs when we want to expand single disk raid0 array.
This is done via degraded 2 disks raid4 array. When new spare
is added to array, md immediately initiates recovery before
mdadm can configure and start reshape. This is due fact that 2 disk
raid4/5 array is special md case. Mdmon does nothing here because
container is blocked.
Put array in to frozen state allows mdadm to finish configuration
before reshape is executed in md.

Signed-off-by: Adam Kwolek <adam.kwolek@intel.com>
Signed-off-by: NeilBrown <neilb@suse.de>