[components][lwIP] Change the lwIP default selected version to 2.0.2.

Author: armink

components/net/Kconfig

@@ -9,7 +9,7 @@ config RT_USING_LWIP
     if RT_USING_LWIP
         choice
             prompt "lwIP version"
-            default RT_USING_LWIP141
+            default RT_USING_LWIP202
             help
                 Select the lwIP version