Fix the compatibility issue of ocrnet on paddlepaddle 2.1

modules/image/semantic_segmentation/ocrnet_hrnetw18_voc/layers.py

@@ -15,7 +15,6 @@
 import paddle
 import paddle.nn as nn
 import paddle.nn.functional as F
-from paddle.nn.layer import activation
 from paddle.nn import Conv2D, AvgPool2D
 
 
@@ -214,7 +213,7 @@ class Activation(nn.Layer):
         super(Activation, self).__init__()
 
         self._act = act
-        upper_act_names = activation.__all__
+        upper_act_names = nn.layer.activation.__dict__.keys()
         lower_act_names = [act.lower() for act in upper_act_names]
         act_dict = dict(zip(lower_act_names, upper_act_names))