add alias for RNN APIs from paddle.nn.layer.rnn explicitly (#27784)

python/paddle/nn/__init__.py

@@ -148,10 +148,17 @@ from .layer.norm import InstanceNorm3d  #DEFINE_ALIAS
 from .layer.norm import BatchNorm1d  #DEFINE_ALIAS
 from .layer.norm import BatchNorm2d  #DEFINE_ALIAS
 from .layer.norm import BatchNorm3d  #DEFINE_ALIAS
-from .layer.rnn import *
-# from .layer.rnn import RNNCell        #DEFINE_ALIAS
-# from .layer.rnn import GRUCell        #DEFINE_ALIAS
-# from .layer.rnn import LSTMCell        #DEFINE_ALIAS
+
+from .layer.rnn import RNNCellBase  #DEFINE_ALIAS
+from .layer.rnn import SimpleRNNCell  #DEFINE_ALIAS
+from .layer.rnn import LSTMCell  #DEFINE_ALIAS
+from .layer.rnn import GRUCell  #DEFINE_ALIAS
+from .layer.rnn import RNN  #DEFINE_ALIAS
+from .layer.rnn import BiRNN  #DEFINE_ALIAS
+from .layer.rnn import SimpleRNN  #DEFINE_ALIAS
+from .layer.rnn import LSTM  #DEFINE_ALIAS
+from .layer.rnn import GRU  #DEFINE_ALIAS
+
 from .layer.transformer import MultiHeadAttention
 from .layer.transformer import TransformerEncoderLayer
 from .layer.transformer import TransformerEncoder