使用 DMA-BUF 分配内存，修复功能bug

configs/sample_ai_pipeline.json

@@ -51,6 +51,17 @@
           "font_scale": 1,
           "labels": []
         },
+        {
+          "id": "post_cam1",
+          "type": "preprocess",
+          "role": "filter",
+          "enable": true,
+          "dst_w": 640,
+          "dst_h": 640,
+          "dst_format": "nv12",
+          "keep_ratio": false,
+          "use_rga": true
+        },
         {
           "id": "pub_cam1",
           "type": "publish",
@@ -72,7 +83,8 @@
         ["in_cam1", "pre_cam1"],
         ["pre_cam1", "ai_cam1"],
         ["ai_cam1", "osd_cam1"],
-        ["osd_cam1", "pub_cam1"]
+        ["osd_cam1", "post_cam1"],
+        ["post_cam1", "pub_cam1"]
       ]
     }
   ]