imsm: FIX: Migration Raid0->Raid5 cannot be restarted correctly

imsm: FIX: Migration Raid0->Raid5 cannot be restarted correctly

When array raid0 is migrated to raid5, reshape cannot be continued
correctly due to wrong array parameters settings.
Raid disks number is set too big.

There is no need, during raid0->raid5 migration to increase
info->array.raid_disks, it is already set to final value using
designation map information.

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