change 4d radar code. not complete.

src/driver/driver_radar_4d_ars548/ar548pac.cpp

@@ -146,6 +146,7 @@ void ars548pac::DecodeDetect()
 
 
     int ndatalen = mPayload.nDataLen;
+    (void)ndatalen;
     char * ppayload = mPayload.pPayload_ptr.get();
 
     int nPos = 0;