[Fix] Fix RPN visualization (#9151)

* [Fix] Fix RPN visualization

* [Fix] Fix RPN visualization

mmdet/models/detectors/rpn.py

@@ -1,5 +1,6 @@
 # Copyright (c) OpenMMLab. All rights reserved.
 import warnings
+from inspect import signature
 
 import mmcv
 import torch
@@ -153,7 +154,9 @@ class RPN(BaseDetector):
             np.ndarray: The image with bboxes drawn on it.
         """
         if kwargs is not None:
-            kwargs.pop('score_thr', None)
-            kwargs.pop('text_color', None)
-            kwargs['colors'] = kwargs.pop('bbox_color', 'green')
+            kwargs['colors'] = 'green'
+            sig = signature(mmcv.imshow_bboxes)
+            for k in list(kwargs.keys()):
+                if k not in sig.parameters:
+                    kwargs.pop(k)
         mmcv.imshow_bboxes(data, result, top_k=top_k, **kwargs)