LU-6834 lod: fix idx_array overwritten

LU-6834 lod: fix idx_array overwritten

Compare index with stripe_count -1 , otherwise it will
overwrite the idx_array[] in lod_prep_md_striped_create().

Signed-off-by: wang di <di.wang@intel.com>
Change-Id: Ib116821fb9e9b800752d760c262ded725c55ce0e
Reviewed-on: http://review.whamcloud.com/15572
Tested-by: Jenkins
Reviewed-by: Niu Yawei <yawei.niu@intel.com>
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>