fix ShuffleNetV2 config (#6138)

* fix ShuffleNetV2 x2_0 stage_out_channels

* fix format, test=document_fix

ppdet/modeling/backbones/shufflenet_v2.py

@@ -188,11 +188,10 @@ class ShuffleNetV2(nn.Layer):
         elif scale == 1.5:
             stage_out_channels = [-1, 24, 176, 352, 704, 1024]
         elif scale == 2.0:
-            stage_out_channels = [-1, 24, 224, 488, 976, 2048]
+            stage_out_channels = [-1, 24, 244, 488, 976, 2048]
         else:
             raise NotImplementedError("This scale size:[" + str(scale) +
                                       "] is not implemented!")
-
         self._out_channels = []
         self._feature_idx = 0
         # 1. conv1