Typo Fix for Default Example Inputs to MobilenetV2 Export (#13206)

### Summary
[PR](#13019) forgot to change
the return example input to use the default samoyed dog image when using
real inputs. This PR fixes that typo.

### Test plan
Now the example runners that use the `mv2` export contain the dog image
in the pte by default.

Author: BujSet

examples/models/mobilenet_v2/model.py

@@ -57,7 +57,7 @@ def get_example_inputs(self):
             input_tensor = preprocess(input_image)
             input_batch = input_tensor.unsqueeze(0)
             input_batch = (input_batch,)
-        return (torch.randn(tensor_size),)
+        return input_batch
 
 
 class MV2UntrainedModel(EagerModelBase):