LU-4929 llite: use the correct mode for striped directory

LU-4929 llite: use the correct mode for striped directory

Create striped directory with correct mode, which should be
handling same as mkdir.

Add -m option to setdirstripe so the user can create stripedir
with specified mode.

Signed-off-by: wang di <di.wang@intel.com>
Change-Id: I4d7d186d4c820cfbdddd0aac9012e7e5e2454278
Reviewed-on: http://review.whamcloud.com/10028
Tested-by: Jenkins
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>