dynamic_macro.h: Do not use backlight_toggle if backlight is disabled

Fixes #1199.

quantum/dynamic_macro.h

@@ -48,9 +48,11 @@ enum dynamic_macro_keycodes {
 /* Blink the LEDs to notify the user about some event. */
 void dynamic_macro_led_blink(void)
 {
+#ifdef BACKLIGHT_ENABLE
     backlight_toggle();
     _delay_ms(100);
     backlight_toggle();
+#endif
 }
 
 /* Convenience macros used for retrieving the debug info. All of them