ARM - ADC cleanup (#8385)

ARM - ADC cleanup (#8385)

* Update switch to array to allow custom values

* Add adc keymap

* update docs to reflect alignment of default 10 bit

* start conversion to USE_ADCVn

* samplerate is hella wrong...stub out for now

* basic f1 and f4 functionality

* Tidy up current changes

* Restore old pinToMux function

* Add back sample rate for supported platforms

* F0 compile fixes

* wordsmithery

Co-Authored-By: Ryan <fauxpark@gmail.com>
* Remove reference to avr only function

Co-authored-by: Ryan <fauxpark@gmail.com>