[quant][graphmode][fx] Remove inplace option for convert_fx (#46955)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/46955
Initially we were thinking of adding a `invalidate_quantized_float_parameters` option to free the memory
of quantized floating parameters, but it turns out we will do module swap just like in eager mode for the modules
that are quantized, so the old floating point module will not be referenced after quantization. therefore this feature
is only needed for functionals, since most people are using quantization with modules we may not need this.
we'll revisit after we find there is a need for this.
Test Plan: Imported from OSS
Reviewed By: supriyar
Differential Revision: D24579400
fbshipit-source-id: fbb0e567405dc0604a2089fc001573affdade986
