[IPV6]: Seperate sit driver to extra module

This patch removes the driver of the IPv6-in-IPv4 tunnel driver (sit)
from the IPv6 module. It adds an option to Kconfig which makes it
possible to compile it as a seperate module.

Signed-off-by: Joerg Roedel <joro-lkml@zlug.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c
index 836eecd..dc5765b 100644
--- a/net/ipv6/sit.c
+++ b/net/ipv6/sit.c
@@ -850,3 +850,6 @@
 	inet_del_protocol(&sit_protocol, IPPROTO_IPV6);
 	goto out;
 }
+
+module_init(sit_init);
+module_exit(sit_cleanup);