fix rnn check_type list error (#24346)

* fix rnn check_type list error

* tigger ci, test=develop

* update modify, test=develop

python/paddle/fluid/layers/rnn.py

@@ -494,8 +494,14 @@ def rnn(cell,
     if isinstance(initial_states, (list, tuple)):
         states = map_structure(lambda x: x, initial_states)[0]
         for i, state in enumerate(states):
-            check_variable_and_dtype(state, 'states[' + str(i) + ']',
-                                     ['float32', 'float64'], 'rnn')
+            if isinstance(state, (list, tuple)):
+                for j, state_j in enumerate(state):
+                    check_variable_and_dtype(state_j, 'state_j[' + str(j) + ']',
+                                             ['float32', 'float64'], 'rnn')
+            else:
+                check_variable_and_dtype(state, 'states[' + str(i) + ']',
+                                         ['float32', 'float64'], 'rnn')
+
     check_type(sequence_length, 'sequence_length', (Variable, type(None)),
                'rnn')