Using the example LUT example with an actual board does not work

The example works; but if you remove temp override then the actual board does not actually function with the LUT as it should
See:
```
pi@octopi:~ $ python ./fancontrol.py
LUT: 20 deg C => 0.0% duty cycle
23 deg C => 20.0% duty cycle
25 deg C => 50.0% duty cycle
28 deg C => 75.0% duty cycle
30 deg C => 100.0% duty cycle
Internal temperature: 25 C
Currently running at 1781.590234 RPM
Internal temperature: 26 C
Currently running at 1779.242175 RPM
Internal temperature: 26 C
Currently running at 1781.590234 RPM
Internal temperature: 26 C
Currently running at 1772.234985 RPM

```

I can take a look at the code next week to see if I spy anything

Start with fancontrol.py and reproduce the reported run on an actual EMC2101 board with the temporary override removed. Compare the LUT output and observed fan RPM against the example behavior, then identify the change needed so the board follows the LUT; done means the example works on hardware without the override.

Written by the indexing model from the issue text.