Adjust wiring_analog.c for Attiny841/441

[mschlenker]

Attiny841/44 with 12+5 ADCs use ADMUXA and ADMUXB instead of ADMUX to select analog reference and channel. Just look at hardware/tools/avr/avr/include/avr/iotn841.h and hardware/tools/avr/avr/include/avr/iotn441.h.

The patch attached properly initializes ADMUXA and ADMUXB to make ADC usable, tested with Attiny841, thanks @awatterott for the hint.

wiring_analog_attiny841.txt

[per1234]

If you're proposing a code change it would be better to submit a pull request.

[mschlenker]

@per1234 per1234, thank you for the hint:
#6644