!396 fix example of ControlDepend to ensure pass in gpu and cpu

Merge pull request !396 from zhangbuxue/fix_example_of_controldepend_for_cpu_and_gpu

mindspore/ops/operations/control_ops.py

@@ -51,16 +51,18 @@ class ControlDepend(Primitive):
         >>> class Net(nn.Cell):
         >>>     def __init__(self):
         >>>         super(Net, self).__init__()
-        >>>         self.global_step = mindspore.Parameter(initializer(0, [1]), name="global_step")
-        >>>         self.rate = 0.2
         >>>         self.control_depend = P.ControlDepend()
+        >>>         self.softmax = P.Softmax()
         >>>
-        >>>     def construct(self, x):
-        >>>         data = self.rate * self.global_step + x
-        >>>         added_global_step = self.global_step + 1
-        >>>         self.global_step = added_global_step
-        >>>         self.control_depend(data, added_global_step)
-        >>>         return data
+        >>>     def construct(self, x, y):
+        >>>         mul = x * y
+        >>>         softmax = self.softmax(x)
+        >>>         ret = self.control_depend(mul, softmax)
+        >>>         return ret
+        >>> x = Tensor(np.ones([4, 5]), dtype=mindspore.float32)
+        >>> y = Tensor(np.ones([4, 5]), dtype=mindspore.float32)
+        >>> net = Net()
+        >>> output = net(x, y)
     """
 
     @prim_attr_register