Move rgblight and backlight task to common location (#7733)

quantum/quantum.c

@@ -634,12 +634,8 @@ void matrix_scan_quantum() {
     matrix_scan_combo();
 #endif
 
-#if defined(BACKLIGHT_ENABLE)
-#    if defined(LED_MATRIX_ENABLE)
+#ifdef LED_MATRIX_ENABLE
     led_matrix_task();
-#    elif defined(BACKLIGHT_PIN) || defined(BACKLIGHT_PINS)
-    backlight_task();
-#    endif
 #endif
 
 #ifdef RGB_MATRIX_ENABLE