/* Free previously allocated USBD event. 
Should be called after usbd_evt_get(). */
static void usbd_evt_free(struct usbd_event *ev)
/* Free previously allocated USBD event. 
Should be called after usbd_evt_get(). */
static void usbd_evt_free(struct usbd_event *ev)
{
	k_mem_slab_free(&fifo_elem_slab, (void *)ev->block.data);
}