Fix USB initilaize on LUFA

- Add print messages of USB intialize procesure.
- call out sei() in earlier stage. LUFA API doc of USB_Init() says:
interrupts must be enabled within 500ms ... to ensure that the host does
not time out whilst enumerating the device
- remove matrix_init() from suspend_wakeup_init(). It is not needed in
  fact and if matrix_init() takes long time to initialize it prevents
host emnumerating the device.

common/keyboard.c

@@ -54,9 +54,6 @@ static bool has_ghost_in_row(uint8_t row)
 
 void keyboard_init(void)
 {
-    // TODO: configuration of sendchar impl
-    print_set_sendchar(sendchar);
-
     timer_init();
     matrix_init();
 #ifdef PS2_MOUSE_ENABLE