!2192 fix cpu lstm bug when hidden_size is zero

Merge pull request !2192 from baihuawei/cpulstm

mindspore/nn/layer/lstm.py

@@ -23,6 +23,7 @@ from mindspore.common.parameter import Parameter, ParameterTuple
 from mindspore.common.tensor import Tensor
 from mindspore.nn.cell import Cell
 from mindspore.ops import operations as P
+from ..._checkparam import Rel
 
 __all__ = ['LSTM', 'LSTMCell']
 
@@ -123,6 +124,8 @@ class LSTM(Cell):
         self.num_layers = num_layers
         self.has_bias = has_bias
         self.batch_first = validator.check_value_type("batch_first", batch_first, [bool], self.cls_name)
+        self.hidden_size = validator.check_integer("hidden_size", hidden_size, 0, Rel.GT, self.cls_name)
+        self.num_layers = validator.check_integer("num_layers", num_layers, 0, Rel.GT, self.cls_name)
         self.dropout = float(dropout)
         self.bidirectional = bidirectional
         if self.batch_first: