[IPV6]: Build modular by default.

Signed-off-by: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/Kconfig

@@ -109,6 +109,7 @@ source "net/ipv4/Kconfig"
 config IPV6
 	tristate "The IPv6 protocol"
 	depends on INET
+	default m
 	select CRYPTO if IPV6_PRIVACY
 	select CRYPTO_MD5 if IPV6_PRIVACY
 	---help---