In [018dbcfd6679c273842084ce34c167295bc6f354](018dbcfd66),
Zephyr introduced the -Wdouble-promotion compiler flag.
We have some debugging logs that implicitly promote floats to double,
and it generates a lot of warnings. This commit fixes it.
The ADC sometimes responds with negative voltages read on the ADC input due to noise. This can lead to very high illuminance readings at night (4095 << 4 to be exact due to two's complement :) ).
This commit caps ADC readings at 0.
This will enable us to transparently use different calibration for
different board revisions. The 2.0.0 revision changes the sensing
circuitry and will need its own coeffs.
In this commit, both models are run in parallel for debugging.
