[Enhance]: Use mmcv root model registry.
# Copyright (c) OpenMMLab. All rights reserved.
+from mmcv.cnn import MODELS as MMCV_MODELS
from mmcv.utils import Registry
-MODELS = Registry('model')
-BACKBONES = Registry('backbone')
-COMPONENTS = Registry('component')
-LOSSES = Registry('loss')
+MODELS = Registry('model', parent=MMCV_MODELS)
+BACKBONES = MODELS
+COMPONENTS = MODELS
+LOSSES = MODELS
