rbd: fix a memory leak in rbd_get_client()

If an existing rbd client is found to be suitable for use in
rbd_get_client(), the rbd_options structure is not being
freed as it should.  Fix that.
Signed-off-by: Alex Elder <elder@dreamhost.com>
Signed-off-by: Sage Weil <sage@newdream.net>

drivers/block/rbd.c

@@ -380,6 +380,7 @@ static int rbd_get_client(struct rbd_device *rbd_dev, const char *mon_addr,
 	rbdc = __rbd_client_find(opt);
 	if (rbdc) {
 		ceph_destroy_options(opt);
+		kfree(rbd_opts);
 
 		/* using an existing client */
 		kref_get(&rbdc->kref);