The thermal monitor measures an NTC thermistor which decreases voltage
when the temperature increases.

When fixing the scaling for the first time, a wrong division by 20 was
removed. The voltage code was still high by a factor of 28900/16384,
enough that the thermal monitor constantly signalled/interrupted at a
low voltage/high temperature trip point. The thermal monitor still
reports the correct temperature so the kernel keeps the wrong trip
points and lets the thermal monitor keep interrupting 1000 times/sec.
Fix the other scaling amount so the thermal monitor sends interrupts at
the right temperature (with some imprecision).