Bug Description

Compare the perf of Torch-TRT against ONNX-TRT:

In fp16:

1. Skipping constant folding of embedding layers doesn't affect engine size or latency or precision
2. Disabling linear decomposition + adding linear converter reduces ~15% latency
3. opt_level=3 or 5 get almost same latency
4. onnx-trt takes much longer in compile time
5. torch-trt is ~9% slower than onnx-trt