Move ocf_request from utils

ocf_request has always been first class citizen in OCF,
so lets place it along with another essential objects.

Signed-off-by: Robert Baldyga <robert.baldyga@intel.com>

src/engine/engine_wi.c

@@ -8,7 +8,7 @@
 #include "engine_wi.h"
 #include "engine_common.h"
 #include "../concurrency/ocf_concurrency.h"
-#include "../utils/utils_req.h"
+#include "../ocf_request.h"
 #include "../utils/utils_cache_line.h"
 #include "../utils/utils_io.h"
 #include "../metadata/metadata.h"