tipc: context imbalance at node read unlock

If we fail to find a valid bearer in tipc_node_get_linkname(),
node_read_unlock() is called without holding the node read lock.

This commit fixes this error.
Signed-off-by: NParthasarathy Bhuvaragan <parthasarathy.bhuvaragan@ericsson.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/tipc/node.c

@@ -1126,8 +1126,8 @@ int tipc_node_get_linkname(struct net *net, u32 bearer_id, u32 addr,
 		strncpy(linkname, tipc_link_name(link), len);
 		err = 0;
 	}
-exit:
 	tipc_node_read_unlock(node);
+exit:
 	tipc_node_put(node);
 	return err;
 }