[quant][graphmode][fx] Keep linear op unchanged when qconfig is not supported (#48067)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/48067
Test Plan: Imported from OSS
Reviewed By: supriyar
Differential Revision: D25008463
fbshipit-source-id: d0bfc6bf8d544824d0a55cd4bcd1f9301d75c935
