node: optick: add support for LXA Optick

The LXA Optick board is an utility for measuring latencies,
that supports both measuring the latencies involved in realtime Linux
and microcontroller applications (on the order of nanoseconds),
as well as light source -> camera -> computer -> display -> light sensor
round trip latencies. (Hence the name, Op-Tick, like being something
visual but also clock like, you know ... a play on words ... nevermind).

The Optick board comes with support hardware for these optical
latency measurements.

The board has two event-generating output ports and two event-capturing
input ports, that capture and generate events relative to a local
64 bit counter running at 48MHz.
The counters from different Optick devices can be synchronized using
the PPS output of a GPS module, to support e.g. time sensitive networking
latency measurements over some distance.

The inputs are analog and feature an on-board comparator that compares
the input voltage to a software configurable reference voltage to form
a basic input trigger.

This commit also contains a commandline utility that implements the basic
optick usecase of measuring a glass to glass camera / display latency,
by first determining the correct trigger level, generating and capturing
events and lastly generating a histogram of measured latencies.

Signed-off-by: Leonard Göhrs <[email protected]>