lcr/vc4080: introduce LCR packet parser for Voltcraft 4080 (and PeakTech 2165)

lcr/vc4080: introduce LCR packet parser for Voltcraft 4080 (and PeakTech 2165)

Introduce the lcr/vc4080.c source file which implements the parser for
the serial data stream of the Voltcraft 4080 LCR meter. Add the meter to
the list of supported devices in the serial-lcr driver, as well as the
PeakTech 2165 LCR meter which is another compatible device.

This implementation contains a workaround for USB based serial cables
which seem to suffer from incomplete parity handling (observed with the
FT232R based PeakTech cable). Similar approaches were seen in existing
DMM drivers.

This implementation supports the main and secondary displays. The D and Q
"displays" which are communicated in the serial packets appear unreliable
and redundant, users can have the D and Q values shown in the supported
displays.