imsm: FIX: spares are not counted

imsm: FIX: spares are not counted

Field info->array.spare_disks is used on begin of reshape_array() to
check if there is enough number of spares to process reshape.  During
container_content_imsm() call spare disks are not counted.  This
causes that reshape_array() reports that there is not enough spares to
execute reshape.

Patch adds spares counting for reshape process.

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