fix(boards): 修复xpython下变量名大小写不敏感

boards/default_src/python/others/names.js

@@ -117,7 +117,7 @@ class Names {
                 name = varName;
             }
         }
-        var normalized = name.toLowerCase() + '_' + type;
+        var normalized = name + '_' + type;
 
         var isVarType = type == Variables.NAME_TYPE ||
             type == Names.DEVELOPER_VARIABLE_TYPE;