Add fix on the bbox loss_weight of the PAA head (#6744)

Co-authored-by: PJLAB\huanghaian <[email protected]>

Author: gkagkos

mmdet/models/dense_heads/paa_head.py

@@ -248,7 +248,7 @@ def get_pos_loss(self, anchors, cls_score, bbox_pred, label, label_weight,
             pos_bbox_pred,
             pos_bbox_target,
             pos_bbox_weight,
-            avg_factor=self.loss_cls.loss_weight,
+            avg_factor=self.loss_bbox.loss_weight,
             reduction_override='none')
 
         loss_cls = loss_cls.sum(-1)