mdadm/grow: adding a test to ensure resize was required

mdadm/grow: adding a test to ensure resize was required

To fix the commit: 4b74a905a67e
(mdadm/grow: Component size must be larger than chunk size)

array.level > 1 : against the raids which chunk_size is meaningful.
s->size > 0 : ensure that changing component size has required.
array.chunk_size / 1024 > s->size : ensure component size should
be always >= current chunk_size when requires resize, otherwise,
mddev->pers->resize would be set mddev->dev_sectors as '0'.

Reported-by: Tomasz Majchrzak <tomasz.majchrzak@intel.com>
Suggested-by: NeilBrown <neilb@suse.com>
Signed-off-by: Zhilong Liu <zlliu@suse.com>
Signed-off-by: Jes Sorensen <jsorensen@fb.com>