Added a build flag for using a custom rgblight driver

quantum/rgblight.c

@@ -364,7 +364,7 @@ void rgblight_setrgb(uint8_t r, uint8_t g, uint8_t b) {
   rgblight_set();
 }
 
-__attribute__ ((weak))
+#ifndef RGBLIGHT_CUSTOM_DRIVER
 void rgblight_set(void) {
   if (rgblight_config.enable) {
     #ifdef RGBW
@@ -385,6 +385,7 @@ void rgblight_set(void) {
     #endif
   }
 }
+#endif
 
 #ifdef RGBLIGHT_ANIMATIONS