Remove observer module after insert_quant_dequant (#29622)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/29622
Remove the observer module in the quantized model
Test Plan: python test/test_jit.py 'TestJit.test_insert_quant_dequant'
Differential Revision: D18442888
Pulled By: jerryzh168
fbshipit-source-id: 22c777569af0e814661fe51f76341b39600fae0d
