[Fix] Fix timm backbone initialization

mmaction/models/recognizers/base.py

@@ -118,13 +118,19 @@ def with_cls_head(self) -> bool:
 
     def init_weights(self) -> None:
         """Initialize the model network weights."""
-        super().init_weights()
         if self.backbone_from in ['torchvision', 'timm']:
             warnings.warn('We do not initialize weights for backbones in '
                           f'{self.backbone_from}, since the weights for '
                           f'backbones in {self.backbone_from} are initialized '
                           'in their __init__ functions.')
 
+            def fake_init():
+                pass
+
+            # avoid repeated initialization
+            self.backbone.init_weights = fake_init
+        super().init_weights()
+
     def loss(self, inputs: torch.Tensor, data_samples: SampleList,
              **kwargs) -> dict:
         """Calculate losses from a batch of inputs and data samples.