Fix RGB / Neopixel white color bug

See #16752

Marlin/src/feature/caselight.cpp

   if (case_light_arg_flag && case_light_on)
     case_light_brightness = case_light_brightness_sav;  // restore last brightens if this is an S1 argument
 
-  #if ENABLED(CASE_LIGHT_USE_NEOPIXEL) || NONE(CASE_LIGHT_USE_NEOPIXEL, CASE_LIGHT_NO_BRIGHTNESS)
+  #if ENABLED(CASE_LIGHT_USE_NEOPIXEL) || DISABLED(CASE_LIGHT_NO_BRIGHTNESS)
     const uint8_t i = case_light_on ? case_light_brightness : 0, n10ct = INVERT_CASE_LIGHT ? 255 - i : i;
   #endif
 

Marlin/src/feature/leds/leds.h

   #include "neopixel.h"
 #endif
 
+// A white component can be passed
 #define HAS_WHITE_LED EITHER(RGBW_LED, NEOPIXEL_LED)
 
 /**
 #define LEDColorBlue()            LEDColor(  0,   0, 255)
 #define LEDColorIndigo()          LEDColor(  0, 255, 255)
 #define LEDColorViolet()          LEDColor(255,   0, 255)
-#if HAS_WHITE_LED
+#if HAS_WHITE_LED && DISABLED(RGB_LED)
   #define LEDColorWhite()         LEDColor(  0,   0,   0, 255)
 #else
   #define LEDColorWhite()         LEDColor(255, 255, 255)

Marlin/src/feature/leds/printer_event_leds.h

   #endif
 
   #if HAS_TEMP_HOTEND || HAS_HEATED_BED
-    static inline void onHeatingDone() { leds.set_color(LEDColorWhite()); }
+    static inline void onHeatingDone() { leds.set_white(); }
     static inline void onPidTuningDone(LEDColor c) { leds.set_color(c); }
   #endif
 

buildroot/share/tests/megaatmega2560-tests

 opt_set FANMUX0_PIN 53
 opt_disable USE_WATCHDOG
 opt_enable REPRAP_DISCOUNT_SMART_CONTROLLER LCD_PROGRESS_BAR LCD_PROGRESS_BAR_TEST \
-           PIDTEMPBED FIX_MOUNTED_PROBE Z_SAFE_HOMING CODEPENDENT_XY_HOMING \
+           FIX_MOUNTED_PROBE Z_SAFE_HOMING CODEPENDENT_XY_HOMING PIDTEMPBED \
+           PROBING_HEATERS_OFF PROBING_FANS_OFF PROBING_STEPPERS_OFF WAIT_FOR_BED_HEATER \
            EEPROM_SETTINGS SDSUPPORT SD_REPRINT_LAST_SELECTED_FILE BINARY_FILE_TRANSFER \
            BLINKM PCA9632 RGB_LED RGB_LED_R_PIN RGB_LED_G_PIN RGB_LED_B_PIN LED_CONTROL_MENU \
            NEOPIXEL_LED CASE_LIGHT_ENABLE CASE_LIGHT_USE_NEOPIXEL CASE_LIGHT_MENU \
            BACKLASH_COMPENSATION BACKLASH_GCODE BAUD_RATE_GCODE BEZIER_CURVE_SUPPORT \
            FWRETRACT ARC_P_CIRCLES CNC_WORKSPACE_PLANES CNC_COORDINATE_SYSTEMS \
            PSU_CONTROL AUTO_POWER_CONTROL POWER_LOSS_RECOVERY POWER_LOSS_PIN POWER_LOSS_STATE \
-           SLOW_PWM_HEATERS THERMAL_PROTECTION_CHAMBER LIN_ADVANCE \
+          SLOW_PWM_HEATERS THERMAL_PROTECTION_CHAMBER LIN_ADVANCE \
            HOST_ACTION_COMMANDS HOST_PROMPT_SUPPORT PINS_DEBUGGING MAX7219_DEBUG M114_DETAIL
 exec_test $1 $2 "RAMPS | EXTRUDERS 2 | CHAR LCD + SD | FIX Probe | ABL-Linear | Advanced Pause | PLR | LEDs ..."