!9952 Fix a bug in categorical distribution

From: @shallydeng
Reviewed-by: @zichun_ye,@sunnybeike
Signed-off-by: @sunnybeike

mindspore/nn/probability/distribution/categorical.py

@@ -175,7 +175,6 @@ class Categorical(Distribution):
         self.squeeze_last_axis = P.Squeeze(-1)
         self.square = P.Square()
         self.transpose = P.Transpose()
-        self.is_nan = P.IsNan()
 
         self.index_type = mstype.int32
         self.nan = np.nan
@@ -291,10 +290,6 @@ class Categorical(Distribution):
         value = self.cast(value, self.dtypeop(probs))
 
         zeros = self.fill(self.dtypeop(value), self.shape(value), 0.0)
-        neg_one = self.fill(self.dtypeop(value), self.shape(value), -1.0)
-        value = self.select(self.is_nan(value),
-                            neg_one,
-                            value)
         between_zero_neone = self.logicand(self.less(value, 0,),
                                            self.greater(value, -1.))
         value = self.select(between_zero_neone,
@@ -359,10 +354,6 @@ class Categorical(Distribution):
         value = self.cast(value, self.dtypeop(probs))
 
         zeros = self.fill(self.dtypeop(value), self.shape(value), 0.0)
-        neg_one = self.fill(self.dtypeop(value), self.shape(value), -1.0)
-        value = self.select(self.is_nan(value),
-                            neg_one,
-                            value)
         between_zero_neone = self.logicand(self.less(value, 0,),
                                            self.greater(value, -1.))
         value = self.select(between_zero_neone,