board_inspector: fix returning nested local variables

Local variables can be assigned with formal arguments in AML. As a result
when interpreting a DefReturn node, the interpreter shall unwrap multiple
layers of argument/local variable wrappings until a concrete value is
found. This patch implements this logic.

Tracked-On: #6287
Signed-off-by: Junjie Mao <junjie.mao@intel.com>

misc/config_tools/board_inspector/acpiparser/aml/interpreter.py

@@ -357,7 +357,7 @@ class ConcreteInterpreter(Interpreter):
 
     def DefReturn(self, tree):
         obj = self.interpret(tree.children[0])
-        if isinstance(obj, (self.Argument, self.LocalVariable)):
+        while isinstance(obj, (self.Argument, self.LocalVariable)):
             obj = obj.get_obj()
         self.stack[-1].return_value = obj
         raise MethodReturn()