thermal shouldn't be so twitchy

[Aaron-Hartwig]

If a single measurement comes in over the high input limit, the thermal loop will disable the system. This is aggressive and can cause the system to shutdown with a spurious measurement.

For example, consider this ringbuf that shows a system sitting with 0% PWM and then being shut down due to a single spurious measurement:

  27  982        4     4328 ControlPwm(0x0)
  28  897        4        1 AutoState(Uncontrollable)
  29  986        4        1 PowerDownAt(0x49f6e3)
  30  770        4        1 PowerModeChanged(PowerBitmask(0b1))