LU-16527 llite: dir layout inheritance fixes

LU-16527 llite: dir layout inheritance fixes

fixes for some minor problems:
- it may happen that the depth is not set on a dir, do not consider
  depth == 0 as a real depth while checking if the root default is
  applicable;
- setdirstripe util implicitely sets max_inherit to 3 for non-striped
  dir when -i option is given but -c is not; at the same time 3 is the
  default for striped dirs only;
- getdirstripe shows inherited default layouts with max_inherit==0,
  whereas it has no sense anymore; the same for an explicitely set
  default layout on a dir/root with max_inherit==0;
- getdirstripe hides max_inherit_rr when stripe_offset != -1 as it has
  no sense and reset to 0, however it leads to user confusion;

HPE-bug-id: LUS-11090
Signed-off-by: Vitaly Fertman <c17818@cray.com>
Change-Id: I65daaac76533fad44a88e1c5a8aad4467c9f7682
Reviewed-on: https://es-gerrit.dev.cray.com/161035
Reviewed-by: Alexander Boyko <alexander.boyko@hpe.com>
Reviewed-by: Alexey Lyashkov <alexey.lyashkov@hpe.com>
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/49882
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Lai Siyao <lai.siyao@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>