kill voltage divider for lower fan

[dankamongmen]

now that we're only taking 3.3V up to the miniboard, we can rearrange things so that both 12V and 3.3V get to the lower fan hookup, eliminating the need for the voltage divider from the 12V line to LTach. make it so. this should be done for the 2.2.0 PCB.

[dankamongmen]

done. we eliminated one resistor entirely, and the other is now a 680 instead of 6.8k, which ought eliminate a component charge from JLCPCB.