LU-14448 lod: verify LOV before set/inherit

LU-14448 lod: verify LOV before set/inherit

DoM layout can only be set as entry in composite layout, and its
stripe count should always be 0.

Verify LOV before setting and inheriting.

Add sanity 270i.

Lustre-change: https://review.whamcloud.com/45039
Lustre-commit: TBD (from f6cb64a29f6445356e0557597ddf83e761de8ca1)

Signed-off-by: Lai Siyao <lai.siyao@whamcloud.com>
Change-Id: I016d1a202960bfebc72dd808de5f80e09051a01e
Signed-off-by: Minh Diep <mdiep@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/45204
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>