Use ADC_RESOLUTION 12 for all STM32 (#20562)

buildroot/share/PlatformIO/variants/MARLIN_FYSETC_S6/variant.h

 #define NUM_ANALOG_INPUTS       7
 #define NUM_ANALOG_FIRST        80
 
-#define ADC_RESOLUTION          12
+//#define ADC_RESOLUTION          12
 
 // PWM resolution
-// #define PWM_RESOLUTION          12
+//#define PWM_RESOLUTION          12
 #define PWM_FREQUENCY           20000 // >= 20 Khz => inaudible noise for fans
 #define PWM_MAX_DUTY_CYCLE      255
 

platformio.ini

   -std=gnu++14
   -DUSBCON -DUSBD_USE_CDC
   -DTIM_IRQ_PRIO=13
+  -DADC_RESOLUTION=12
 build_unflags = -std=gnu++11
 src_filter    = ${common.default_src_filter} +<src/HAL/STM32> +<src/HAL/shared/backtrace>