V4L/DVB (7806): em28xx: dvb_unregister_frontend() shouldn't be called, if not registered yet

Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

drivers/media/video/em28xx/em28xx-dvb.c

@@ -251,7 +251,6 @@ static int attach_xc3028(u8 addr, struct em28xx *dev)
 		printk(KERN_ERR "%s/2: xc3028 attach failed\n",
 		       dev->name);
 		dvb_frontend_detach(dev->dvb->frontend);
-		dvb_unregister_frontend(dev->dvb->frontend);
 		dev->dvb->frontend = NULL;
 		return -EINVAL;
 	}