[PPPOL2TP]: Add CONFIG_INET Kconfig dependency.

PPPOL2TP uses UDP so it obviously depends on CONFIG_INET.

Signed-off-by: James Chapman <jchapman@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig
index f8a602c..81ef81c 100644
--- a/drivers/net/Kconfig
+++ b/drivers/net/Kconfig
@@ -2851,7 +2851,7 @@
 
 config PPPOL2TP
 	tristate "PPP over L2TP (EXPERIMENTAL)"
-	depends on EXPERIMENTAL && PPP
+	depends on EXPERIMENTAL && PPP && INET
 	help
 	  Support for PPP-over-L2TP socket family. L2TP is a protocol
 	  used by ISPs and enterprises to tunnel PPP traffic over UDP