MLECO-3076: Add use case API for object detection

* Removed unused prototype for box drawing

Signed-off-by: Richard Burton <richard.burton@arm.com>
Change-Id: I1b03b88e710a5efb1ff8e107859d2245b1fead26
diff --git a/tests/use_case/object_detection/InferenceTestYoloFastest.cc b/tests/use_case/object_detection/InferenceTestYoloFastest.cc
index 8ef012d..2c035e7 100644
--- a/tests/use_case/object_detection/InferenceTestYoloFastest.cc
+++ b/tests/use_case/object_detection/InferenceTestYoloFastest.cc
@@ -94,13 +94,8 @@
         REQUIRE(tflite::GetTensorData<T>(output_arr[i]));
     }
 
-    arm::app::object_detection::DetectorPostprocessing postp;
-    postp.RunPostProcessing(
-        nRows,
-        nCols,
-        output_arr[0],
-        output_arr[1],
-        results);
+    arm::app::DetectorPostProcess postp{output_arr[0], output_arr[1], results, nRows, nCols};
+    postp.DoPostProcess();
 
     std::vector<std::vector<arm::app::object_detection::DetectionResult>> expected_results;
     GetExpectedResults(expected_results);