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/include/net/transp_v6.h b/include/net/transp_v6.h
index 112934a..876b6f2 100644
--- a/include/net/transp_v6.h
+++ b/include/net/transp_v6.h
@@ -53,7 +53,7 @@
  */
 extern struct inet_connection_sock_af_ops ipv4_specific;
 
-extern int inet6_destroy_sock(struct sock *sk);
+extern void inet6_destroy_sock(struct sock *sk);
 
 #endif