vt: drop unused struct vt_struct

#include <linux/vt.h>

#include <linux/workqueue.h>

struct vt_struct;

struct uni_pagedir;

struct uni_screen;

	struct vc_data *d;

	struct work_struct SAK_work;

	/* might add  scrmem, vt_struct, kbd  at some time,

	/* might add  scrmem, kbd  at some time,

	   to have everything in one place - the disadvantage

	   would be that vc_cons etc can no longer be static */

};