Typo in usage example, changed to device instead of torch_device (#11979)

docs/source/model_doc/pegasus.rst

@@ -90,7 +90,7 @@ Usage Example
     >>> device = 'cuda' if torch.cuda.is_available() else 'cpu'
     >>> tokenizer = PegasusTokenizer.from_pretrained(model_name)
     >>> model = PegasusForConditionalGeneration.from_pretrained(model_name).to(device)
-    >>> batch = tokenizer(src_text, truncation=True, padding='longest', return_tensors="pt").to(torch_device)
+    >>> batch = tokenizer(src_text, truncation=True, padding='longest', return_tensors="pt").to(device)
     >>> translated = model.generate(**batch)
     >>> tgt_text = tokenizer.batch_decode(translated, skip_special_tokens=True)
     >>> assert tgt_text[0] == "California's largest electricity provider has turned off power to hundreds of thousands of customers."