lavfi/dnn_backend_openvino.c: Fix Memory Leak in execute_model_ov

In cases where the execution inside the function execute_model_ov fails,
push the RequestItem back to the request_queue before returning the error.
In case pushing back fails, release the allocated memory.

Signed-off-by: Shubhanshu Saxena <shubhanshu.e01@gmail.com>

libavfilter/dnn/dnn_backend_openvino.c

@@ -448,12 +448,12 @@ static DNNReturnType execute_model_ov(RequestItem *request, Queue *inferenceq)
         status = ie_infer_set_completion_callback(request->infer_request, &request->callback);
         if (status != OK) {
             av_log(ctx, AV_LOG_ERROR, "Failed to set completion callback for inference\n");
-            return DNN_ERROR;
+            goto err;
         }
         status = ie_infer_request_infer_async(request->infer_request);
         if (status != OK) {
             av_log(ctx, AV_LOG_ERROR, "Failed to start async inference\n");
-            return DNN_ERROR;
+            goto err;
         }
         return DNN_SUCCESS;
     } else {
@@ -464,11 +464,17 @@ static DNNReturnType execute_model_ov(RequestItem *request, Queue *inferenceq)
         status = ie_infer_request_infer(request->infer_request);
         if (status != OK) {
             av_log(ctx, AV_LOG_ERROR, "Failed to start synchronous model inference\n");
-            return DNN_ERROR;
+            goto err;
         }
         infer_completion_callback(request);
         return (task->inference_done == task->inference_todo) ? DNN_SUCCESS : DNN_ERROR;
     }
+err:
+    if (ff_safe_queue_push_back(ov_model->request_queue, request) < 0) {
+        ie_infer_request_free(&request->infer_request);
+        av_freep(&request);
+    }
+    return DNN_ERROR;
 }
 
 static DNNReturnType get_input_ov(void *model, DNNData *input, const char *input_name)