libnl_2: Add nl_socket_set_cb() and nl_socket_get_cb()

Change-Id: Ibc2b4dc9528bd43d3fc85491c4838a33c916330e
Signed-off-by: Dmitry Shmidt <dimitrysh@google.com>
diff --git a/libnl_2/socket.c b/libnl_2/socket.c
index d906cac..e94eb9e 100644
--- a/libnl_2/socket.c
+++ b/libnl_2/socket.c
@@ -127,3 +127,15 @@
 {
 	return sk->s_fd;
 }
+
+void nl_socket_set_cb(struct nl_sock *sk, struct nl_cb *cb)
+{
+	nl_cb_put(sk->s_cb);
+	sk->s_cb = cb;
+	nl_cb_get(cb);
+}
+
+struct nl_cb *nl_socket_get_cb(struct nl_sock *sk)
+{
+	return nl_cb_get(sk->s_cb);
+}