sk-netlink: typo fix for unconnected netlink sockets

The netlink_diag doesn't provide any info about non-connected and
non-bound sockets.
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

sk-netlink.c

@@ -91,7 +91,7 @@ static int dump_one_netlink_fd(int lfd, u32 id, const struct fd_parms *p)
 	SkOptsEntry skopts = SK_OPTS_ENTRY__INIT;
 
 	sk = (struct netlink_sk_desc *)lookup_socket(p->stat.st_ino, PF_NETLINK, 0);
-	if (IS_ERR_OR_NULL(sk))
+	if (IS_ERR(sk))
 		goto err;
 
 	ne.id = id;