Allow ACPI to set fan speeds

[curiousercreative]

• Relays ACPI writes to ACPI fan variables
• Fan speeds will be a smoothed maximum of what EC would set and what ACPI has requested.
• Needs testing, ACPI requested speeds that differ when multiple fans present may override the EC fan syncing, which should be okay. If userspace wants control, allow them to control the fan speeds independently.

Futher discussion/consideration should be had on:

• Should EC set fan speed floors or not spin fans at all? I currently have EC set floors.
• Should EC be responsible for smoothing fan speeds when ACPI values are used? I currently have EC smoothing always, but this yields poor pwmconfig detection. A PR exists for not smoothing ACPI values here
• Depending on the above, we should revisit the existing fan curves and perhaps make them far more conservative and push any fan speed "performance" concerns to userspace.

Relates to:

• Add ACPI methods for setting fan speed coreboot#143
• Make laptop fan duty pwm writable pop-os/system76-acpi-dkms#18

[curiousercreative]

rebased and tested on my galp5

[crawfxrd]

Implementing manual fan control in #512, which will allow system firmware or OS to set fan target duty without conflict from EC.