Remove low-level stats getters from public API.

Since stats builder is implemented for retrieving cache, core and ioclass stats,
adapters should use it instead.

Signed-off-by: Michal Mielewczyk <michal.mielewczyk@intel.com>

inc/ocf.h

@@ -29,7 +29,6 @@
 #include "ocf_metadata_updater.h"
 #include "ocf_io_class.h"
 #include "ocf_stats.h"
-#include "ocf_stats_builder.h"
 #include "ocf_mngt.h"
 #include "ocf_ctx.h"
 #include "ocf_err.h"