perf tools: new naming convention for openCSD

The naming convention for the openCSD API and header files
was changed so that using it was easier.  Headers went from
"rctdl_xyz.h" to "opencsd_xyz.h" while internal symbol from
"rctdl_" to "ocsd_".

Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>