fou: fix IPv6 Kconfig options

The Kconfig options I added to work around broken compilation ended
up screwing up things more, as I used the wrong symbol to control
compilation of the file, resulting in IPv6 fou support to never be built
into the kernel.

Changing CONFIG_NET_FOU_IPV6_TUNNELS to CONFIG_IPV6_FOU fixes that
problem, I had renamed the symbol in one location but not the other,
and as the file is never being used by other kernel code, this did not
lead to a build failure that I would have caught.

After that fix, another issue with the same patch becomes obvious, as we
'select INET6_TUNNEL', which is related to IPV6_TUNNEL, but not the same,
and this can still cause the original build failure when IPV6_TUNNEL is
not built-in but IPV6_FOU is. The fix is equally trivial, we just need
to select the right symbol.

I have successfully build 350 randconfig kernels with this patch
and verified that the driver is now being built.
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Reported-by: NValentin Rothberg <valentinrothberg@gmail.com>
Fixes: fabb13db ("fou: add Kconfig options for IPv6 support")
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv6/Kconfig

@@ -239,7 +239,7 @@ config IPV6_FOU
 config IPV6_FOU_TUNNEL
 	tristate
 	default NET_FOU_IP_TUNNELS && IPV6_FOU
-	select INET6_TUNNEL
+	select IPV6_TUNNEL
 
 config IPV6_MULTIPLE_TABLES
 	bool "IPv6: Multiple Routing Tables"

net/ipv6/Makefile

@@ -42,7 +42,7 @@ obj-$(CONFIG_IPV6_VTI) += ip6_vti.o
 obj-$(CONFIG_IPV6_SIT) += sit.o
 obj-$(CONFIG_IPV6_TUNNEL) += ip6_tunnel.o
 obj-$(CONFIG_IPV6_GRE) += ip6_gre.o
-obj-$(CONFIG_NET_FOU_IPV6_TUNNELS) += fou6.o
+obj-$(CONFIG_IPV6_FOU) += fou6.o
 
 obj-y += addrconf_core.o exthdrs_core.o ip6_checksum.o ip6_icmp.o
 obj-$(CONFIG_INET) += output_core.o protocol.o $(ipv6-offload)