LU-13687 llite: return -ENODATA if no default layout

LU-13687 llite: return -ENODATA if no default layout

Don't return -ENOENT if fetching the default layout from the root
directory fails.  Otherwise, "lfs find" will print an error message
for every directory scanned in the filesystem:

     lfs find: /myth/tmp does not exist: No such file or directory

Fixes: 3e8fa8a7396c ("LU-11656 llite: fetch default layout for a directory")
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Change-Id: I5e082c5d425c44ca7770d3b24cbb13bb7d2540e5
Reviewed-on: https://review.whamcloud.com/39200
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Jian Yu <yujian@whamcloud.com>
Reviewed-by: Lai Siyao <lai.siyao@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Oleg Drokin <green@whamcloud.com>