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/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index ebed5d3..daefc18 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1872,7 +1872,7 @@
 	return 0;
 }
 
-static int tcp_v6_destroy_sock(struct sock *sk)
+static void tcp_v6_destroy_sock(struct sock *sk)
 {
 #ifdef CONFIG_TCP_MD5SIG
 	/* Clean up the MD5 key list */
@@ -1880,7 +1880,7 @@
 		tcp_v6_clear_md5_list(sk);
 #endif
 	tcp_v4_destroy_sock(sk);
-	return inet6_destroy_sock(sk);
+	inet6_destroy_sock(sk);
 }
 
 #ifdef CONFIG_PROC_FS