net: use IS_ENABLED(CONFIG_IPV6)

Instead of testing defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
index 3382615..ad0e31b 100644
--- a/include/net/sctp/structs.h
+++ b/include/net/sctp/structs.h
@@ -365,7 +365,7 @@
        return (struct sock *)sp;
 }
 
-#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
+#if IS_ENABLED(CONFIG_IPV6)
 struct sctp6_sock {
        struct sctp_sock  sctp;
        struct ipv6_pinfo inet6;