LU-2190 utils: Use LDD_PREFIX in LDD_*_PROP macros

LU-2190 utils: Use LDD_PREFIX in LDD_*_PROP macros

This patch replaces the hard coded "lustre:" string used in the
LDD_*_PROP macro definitions with the LDD_PREFIX macro. This is
functionally equivalent, but eases the burden if the prefix string
is ever changed (and subjectively makes the code easier to read).

Signed-off-by: Prakash Surya <surya1@llnl.gov>
Change-Id: Ief0e710b90cf922eb4d4cc8a162ee1b0d21317b4
Reviewed-on: http://review.whamcloud.com/5671
Tested-by: Hudson
Reviewed-by: Alex Zhuravlev <alexey.zhuravlev@intel.com>
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>