fan control improvements

[jolan]

• AMDGPU
  • not all values (0-255) are supported so we need to clamp to supported values
  • need to figure out how to restore automatic fan control upon device release like we do for ADL
• General Improvements
  • The whole fanControl() function probably needs to be re-written since it was a quick hack to make sure the fan control functionality was working. Can take some inspiration from sgminer's implementation https://github.com/tpruvot/sgminer/blob/decred/adl.c#L1230-L1301