Update BlinkRGB example

Update example code for changes with the RGB driver:
- Replace `LED_BUILTIN` and `BOARD_HAS_NEOPIXEL` with `RGB_BUILTIN`
- Replace `LED_BRIGHTNESS` with `RGB_BRIGHTNESS`

Author: santaimpersonator

libraries/ESP32/examples/GPIO/BlinkRGB/BlinkRGB.ino

@@ -3,15 +3,15 @@
 
   Demonstrates usage of onboard RGB LED on some ESP dev boards.
 
-  Calling digitalWrite(LED_BUILTIN, HIGH) will use hidden RGB driver.
+  Calling digitalWrite(RGB_BUILTIN, HIGH) will use hidden RGB driver.
     
   RGBLedWrite demonstrates controll of each channel:
   void neopixelWrite(uint8_t pin, uint8_t red_val, uint8_t green_val, uint8_t blue_val)
 
   WARNING: After using digitalWrite to drive RGB LED it will be impossible to drive the same pin
     with normal HIGH/LOW level
 */
-//#define LED_BRIGHTNESS 64 // Change white brightness (max 255)
+//#define RGB_BRIGHTNESS 64 // Change white brightness (max 255)
 
 // the setup function runs once when you press reset or power the board
 
@@ -21,19 +21,19 @@ void setup() {
 
 // the loop function runs over and over again forever
 void loop() {
-#ifdef BOARD_HAS_NEOPIXEL
-  digitalWrite(LED_BUILTIN, HIGH);   // Turn the RGB LED white
+#ifdef RGB_BUILTIN
+  digitalWrite(RGB_BUILTIN, HIGH);   // Turn the RGB LED white
   delay(1000);
-  digitalWrite(LED_BUILTIN, LOW);    // Turn the RGB LED off
+  digitalWrite(RGB_BUILTIN, LOW);    // Turn the RGB LED off
   delay(1000);
 
-  neopixelWrite(LED_BUILTIN,LED_BRIGHTNESS,0,0); // Red
+  neopixelWrite(RGB_BUILTIN,RGB_BRIGHTNESS,0,0); // Red
   delay(1000);
-  neopixelWrite(LED_BUILTIN,0,LED_BRIGHTNESS,0); // Green
+  neopixelWrite(RGB_BUILTIN,0,RGB_BRIGHTNESS,0); // Green
   delay(1000);
-  neopixelWrite(LED_BUILTIN,0,0,LED_BRIGHTNESS); // Blue
+  neopixelWrite(RGB_BUILTIN,0,0,RGB_BRIGHTNESS); // Blue
   delay(1000);
-  neopixelWrite(LED_BUILTIN,0,0,0); // Off / black
+  neopixelWrite(RGB_BUILTIN,0,0,0); // Off / black
   delay(1000);
 #endif
 }