Code fixing Spice device names (prefixing reference with a character
corresponding to the assigned device model type) that was duplicated in
a few places has been moved to a function (NETLIST_EXPORTER_PSPICE::GetSpiceDevice()).
This commit creates more issues than resolves. It could happen that
there are components with different reference types (e.g. U1 and IC1)
that would be later converted to X1, causing a conflict.