vhost: Remove the repeated declaration

Function 'vhost_vring_ioctl' is declared twice, remove the repeated
declaration.

Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Signed-off-by: Shaokun Zhang <zhangshaokun@hisilicon.com>
Link: https://lore.kernel.org/r/1621857884-19964-1-git-send-email-zhangshaokun@hisilicon.comAcked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

drivers/vhost/vhost.h

@@ -47,7 +47,6 @@ void vhost_poll_stop(struct vhost_poll *poll);
 void vhost_poll_flush(struct vhost_poll *poll);
 void vhost_poll_queue(struct vhost_poll *poll);
 void vhost_work_flush(struct vhost_dev *dev, struct vhost_work *work);
-long vhost_vring_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp);
 
 struct vhost_log {
 	u64 addr;