LU-17464 lod: set llc_ostlist to NULL after free

LU-17464 lod: set llc_ostlist to NULL after free

Default LOV striping could free component entry llc_ostlist if needed
e.g. expand component entries, without set it to NULL it could be
double allocated/freed later.

Signed-off-by: Bobi Jam <bobijam@whamcloud.com>
Change-Id: I25824cb61dd47ba284403039259593b88d25fa9d
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/53797
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Qian Yingjin <qian@ddn.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>