LU-12846 mdd: return error while delete failed

LU-12846 mdd: return error while delete failed

Since we use a global buffer, So avoid to replace the
index name while iterate the orphan directory. Also
return error code in mdd_orphan_destroy while dt_delete
failed. Else will cause a dead loop.

Fixes: e1ace3751f ("LU-8514 mdd: transaction failure should be checked")
Signed-off-by: Yang Sheng <ys@whamcloud.com>
Change-Id: I6fc3e992333ffa61900074309223555264cfe66b
Reviewed-on: https://review.whamcloud.com/36602
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Artem Blagodarenko <c17828@cray.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>