[remove] redundant script.

components/net/SConscript

@@ -7,10 +7,6 @@ objs = []
 cwd = GetCurrentDir()
 list = os.listdir(cwd)
 
-# the default version of LWIP is 2.0.2
-if not GetDepend('RT_USING_LWIP141') and not GetDepend('RT_USING_LWIP202') and not GetDepend('RT_USING_LWIP203') and not GetDepend('RT_USING_LWIP212'):
-    AddDepend('RT_USING_LWIP202')
-
 for d in list:
     path = os.path.join(cwd, d)
     if os.path.isfile(os.path.join(path, 'SConscript')):