fix 内存泄漏

app/src/main/java/com/doverfuelingsolutions/issp/driver/serialPort/SerialControl.java

@@ -35,4 +35,11 @@ public class SerialControl extends SerialHelper {
             listener.onDataReceived(ComRecData.bRec);
         }
     }
+
+    @Override
+    public void close() {
+        super.close();
+
+        this.scanValueListener = null;
+    }
 }