net: change proto destroy method to return void

Change struct proto destroy function pointer to return void.  Noticed
by Al Viro.

Signed-off-by: Brian Haley <brian.haley@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/dccp/ipv6.c b/net/dccp/ipv6.c
index f7fe2a5..eec3c47 100644
--- a/net/dccp/ipv6.c
+++ b/net/dccp/ipv6.c
@@ -1091,10 +1091,10 @@
 	return err;
 }
 
-static int dccp_v6_destroy_sock(struct sock *sk)
+static void dccp_v6_destroy_sock(struct sock *sk)
 {
 	dccp_destroy_sock(sk);
-	return inet6_destroy_sock(sk);
+	inet6_destroy_sock(sk);
 }
 
 static struct timewait_sock_ops dccp6_timewait_sock_ops = {