[IPV6]: make inet6_register_protosw to return an error code

This patch makes the inet6_register_protosw to return an error code.
The different protocols can be aware the registration was successful or
not and can pass the error to the initial caller, af_inet6.

Signed-off-by: Daniel Lezcano <dlezcano@fr.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/protocol.h b/include/net/protocol.h
index 1166ffb..ad8c584 100644
--- a/include/net/protocol.h
+++ b/include/net/protocol.h
@@ -102,7 +102,7 @@
 #if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
 extern int	inet6_add_protocol(struct inet6_protocol *prot, unsigned char num);
 extern int	inet6_del_protocol(struct inet6_protocol *prot, unsigned char num);
-extern void	inet6_register_protosw(struct inet_protosw *p);
+extern int	inet6_register_protosw(struct inet_protosw *p);
 extern void	inet6_unregister_protosw(struct inet_protosw *p);
 #endif