[quant][graphmode][fix] Fix insert quant dequant for observers without qparams (#43606)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/43606
Test Plan: Imported from OSS
Reviewed By: vkuzo
Differential Revision: D23335106
fbshipit-source-id: 84af2884d52118c069fc43a9f166dc336a8a87c8
