Update IR for Torch-TensorRT userbenchmark (#1946)

Summary:
- Update IR from `default` to `torch_compile`, to ensure testing is against the desired `torch_compile` backend

Pull Request resolved: #1946

Reviewed By: davidberard98

Differential Revision: D49739908

Pulled By: xuzhao9

fbshipit-source-id: 77b9a6ef2880db8f0b234a552aea27290d559f69

userbenchmark/torch_trt/run.py

@@ -195,7 +195,7 @@ def run(args: List[str]):
         ir_idx = unknown_args.index("--ir")
         selected_ir = unknown_args[ir_idx + 1]
     except (ValueError, IndexError):
-        selected_ir = "default"
+        selected_ir = "torch_compile"
 
     # Parse model string if specified, otherwise run all models
     # Adapted from benchmark/run.py