[fx_acc] Run shape prop at the end of acc tracer (#38)

Summary:
Pull Request resolved: pytorch/fx2trt#38

Populate tensor meta for each node after normalization is done. Lowering quantized model needs qparams in tensor_meta.

Reviewed By: wushirong

Differential Revision: D35191422

fbshipit-source-id: 373fb2b7a81badf476ee2328f3d518d5425b93f3

Author: 842974287

tracer/acc_tracer/acc_tracer.py

@@ -482,4 +482,7 @@ def trace(
 
     traced.recompile()
 
+    # Run shape prop to again to populate tensor_meta after normalize.
+    shape_prop.ShapeProp(traced).propagate(*sample_inputs)
+
     return traced