net: add PPP on L2TP Access Concentrator (PPPoLAC) driver.

Change-Id: I3ae3ee7520951ae24269db0ef2898c6455cf6bcc
Signed-off-by: Chia-chi Yeh <chiachi@android.com>

ppolac: dont include px_proto define in if_pppolac.h

Change-Id: I55bc9cf91ea0e9e8f7bf5d6e241d188e1269343a
Signed-off-by: Dima Zavin <dima@android.com>
diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig
index 19f04a3..5abe1b3 100644
--- a/drivers/net/Kconfig
+++ b/drivers/net/Kconfig
@@ -3323,6 +3323,15 @@
 	  used by ISPs and enterprises to tunnel PPP traffic over UDP
 	  tunnels. L2TP is replacing PPTP for VPN uses.
 
+config PPPOLAC
+	tristate "PPP on L2TP Access Concentrator"
+	depends on PPP && INET
+	help
+	  L2TP (RFC 2661) is a tunneling protocol widely used in virtual private
+	  networks. This driver handles L2TP data packets between a UDP socket
+	  and a PPP channel, but only permits one session per socket. Thus it is
+	  fairly simple and suited for clients.
+
 config SLIP
 	tristate "SLIP (serial line) support"
 	---help---