fix typo

example/rnn/lstm.py

@@ -17,7 +17,7 @@
 def lstm(num_hidden, indata, prev_state, param, seqidx, layeridx, dropout=0.):
     """LSTM Cell symbol"""
     if dropout > 0.:
-        in_data = mx.sym.Dropout(data=in_data, p=dropout)
+        indata = mx.sym.Dropout(data=indata, p=dropout)
     i2h = mx.sym.FullyConnected(data=indata,
                                 weight=param.i2h_weight,
                                 bias=param.i2h_bias,