Kernel: Keyboard event callback can now be registered later

kernel/include/kernel/Keyboard.h

@@ -37,9 +37,11 @@ namespace Keyboard
 		bool	pressed;
 	};
 
-	bool initialize(void (*callback)(KeyEvent));
+	bool initialize();
 	void update_keyboard();
 
+	void register_key_event_callback(void(*callback)(KeyEvent));
+
 	char key_event_to_ascii(KeyEvent);
 
 	void led_disco();