[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/Kconfig b/net/ipv6/Kconfig
index a460e81..ef5eaad 100644
--- a/net/ipv6/Kconfig
+++ b/net/ipv6/Kconfig
@@ -153,6 +153,19 @@
 	---help---
 	  Support for MIPv6 route optimization mode.
 
+config IPV6_SIT
+	tristate "IPv6: IPv6-in-IPv4 tunnel (SIT driver)"
+	depends on IPV6
+	default y
+	---help---
+	  Tunneling means encapsulating data of one protocol type within
+	  another protocol and sending it over a channel that understands the
+	  encapsulating protocol. This driver implements encapsulation of IPv6
+	  into IPv4 packets. This is useful if you want to connect two IPv6
+	  networks over an IPv4-only path.
+
+	  Saying M here will produce a module called sit.ko. If unsure, say Y.
+
 config IPV6_TUNNEL
 	tristate "IPv6: IPv6-in-IPv6 tunnel"
 	select INET6_TUNNEL