vhost: Export vhost_dev_set_owner

Signed-off-by: Asias He <asias@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 749b5ab..de9441a 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -344,7 +344,7 @@
 }
 
 /* Caller should have device mutex */
-static long vhost_dev_set_owner(struct vhost_dev *dev)
+long vhost_dev_set_owner(struct vhost_dev *dev)
 {
 	struct task_struct *worker;
 	int err;