Do not continue reshape during initrd phase

Do not continue reshape during initrd phase

During initrd phase continuing reshape will cause file system context
lost. This blocks ability to control reshape using checkpoints.

To avoid this, during initrd phase assemble has to be executed with
'--freeze-reshape' option. This causes that mdadm restores reshape
critical section only.

Reshape can be continued later after system full boot.

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