vhost: Remove vhost_enable_zcopy in vhost.h

It is net.c specific.
Signed-off-by: NAsias He <asias@redhat.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>

drivers/vhost/vhost.h

@@ -186,7 +186,4 @@ static inline int vhost_has_feature(struct vhost_dev *dev, int bit)
 	acked_features = rcu_dereference_index_check(dev->acked_features, 1);
 	return acked_features & (1 << bit);
 }
-
-void vhost_enable_zcopy(int vq);
-
 #endif