fix enable ADC on pin37,38

[radiumray]

fix enable ADC on gpio37,38
gpio37,38 will enable when make this change.

[me-no-dev]

Thanks :)

[palomarcoder]

Will these pins actually work though, on boards that have the capacitors hard-wired? Do we need to cut the traces to the capacitors? or is there a way to disable the pre-amp?
I've never really seen good documentation on which of these pings can be used and which cannot if the capacitors are in place.