fix dcn r101vd config, test=dygraph (#2223)

dygraph/configs/dcn/faster_rcnn_dcn_r101_vd_fpn_1x_coco.yml

 _BASE_: [
   'faster_rcnn_dcn_r50_fpn_1x_coco.yml',
 ]
-pretrain_weights: https://paddle-imagenet-models-name.bj.bcebos.com/ResNet101_pretrained.tar
-weights: output/faster_rcnn_dcn_r101_fpn_1x_coco/model_final
+pretrain_weights: https://paddle-imagenet-models-name.bj.bcebos.com/ResNet101_vd_pretrained.tar
+weights: output/faster_rcnn_dcn_r101_vd_fpn_1x_coco/model_final
 
 ResNet:
   # index 0 stands for res2

dygraph/configs/dcn/mask_rcnn_dcn_r101_vd_fpn_1x_coco.yml

 _BASE_: [
   'mask_rcnn_dcn_r50_fpn_1x_coco.yml',
 ]
-pretrain_weights: https://paddle-imagenet-models-name.bj.bcebos.com/ResNet101_pretrained.tar
-weights: output/mask_rcnn_dcn_r101_fpn_1x_coco/model_final
+pretrain_weights: https://paddle-imagenet-models-name.bj.bcebos.com/ResNet101_vd_pretrained.tar
+weights: output/mask_rcnn_dcn_r101_vd_fpn_1x_coco/model_final
 
 ResNet:
   # index 0 stands for res2