[lwIP] update net/SConscript for lwip 2.0.0

components/net/SConscript

@@ -8,7 +8,7 @@ cwd = GetCurrentDir()
 list = os.listdir(cwd)
 
 # the default version of LWIP is 1.4.1
-if not GetDepend('RT_USING_LWIP132') and not GetDepend('RT_USING_LWIP140') and not GetDepend('RT_USING_LWIP_HEAD'):
+if not GetDepend('RT_USING_LWIP132') and not GetDepend('RT_USING_LWIP140') and not GetDepend('RT_USING_LWIP200'):
     AddDepend('RT_USING_LWIP141')
 
 for d in list: