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>

keyboards/handwired/onekey/keymaps/adc/keymap.c

@@ -0,0 +1,38 @@
+#include QMK_KEYBOARD_H
+#include "analog.h"
+#include <stdio.h>
+
+#ifndef ADC_PIN
+#    define ADC_PIN A0
+#endif
+
+enum custom_keycodes {
+    ADC_SAMPLE = SAFE_RANGE,
+};
+
+const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
+    LAYOUT(ADC_SAMPLE)  //
+};
+
+bool process_record_user(uint16_t keycode, keyrecord_t *record) {
+    switch (keycode) {
+        case ADC_SAMPLE:
+            if (record->event.pressed) {
+                int16_t val = analogReadPin(ADC_PIN);
+
+                char buffer [50];
+                sprintf(buffer, "ADC:%u\n", val);
+#ifdef CONSOLE_ENABLE
+                    printf(buffer);
+#else
+                    SEND_STRING(buffer);
+#endif
+            }
+            break;
+    }
+    return false;
+};
+
+// adc_mux pinToMux(pin_t pin) {
+//     return TO_MUX( ADC_CHANNEL_IN1,  0 );
+// };