!1285 fix dropout error in pynative mode

Merge pull request !1285 from chujinjin/fix_dropout_in_pynative

mindspore/nn/layer/basic.py

@@ -78,7 +78,7 @@ class Dropout(Cell):
         if keep_prob <= 0 or keep_prob > 1:
             raise ValueError("dropout probability should be a number in range (0, 1], but got {}".format(keep_prob))
         validator.check_subclass("dtype", dtype, mstype.number_type, self.cls_name)
-        self.keep_prob = Tensor(keep_prob)
+        self.keep_prob = keep_prob
         self.seed0 = seed0
         self.seed1 = seed1
         self.dtype = dtype