LU-2902 test: ost stat parameters were not present

A few tests use roc_hit to sort out cache hits. These tests
were failing for a while because the lproc stats needed were not
present.

Use roc_hit_init with setstripe to correctly identify that basic
cache_access stats are working for each individual ost before
using roc_hit.

Signed-off-by: Keith Mannthey <keith.mannthey@intel.com>
Change-Id: Iea501433ddcdb367fe5d9614361b4aff049cb1f1
Reviewed-on: http://review.whamcloud.com/6564
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Jian Yu <jian.yu@intel.com>
Reviewed-by: Bob Glossman <bob.glossman@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>