pppox: use standard module auto-loading feature

* Register PF_PPPOX with pppox module rather than with pppoe,
    so that pppoe doesn't get loaded for any PF_PPPOX socket.

  * Register PX_PROTO_* with standard MODULE_ALIAS_NET_PF_PROTO()
    instead of using pppox's own naming scheme.

  * While there, add auto-loading feature for pptp.

Signed-off-by: Guillaume Nault <g.nault@alphalink.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/l2tp/l2tp_ppp.c b/net/l2tp/l2tp_ppp.c
index 1ad18c5..d93f113 100644
--- a/net/l2tp/l2tp_ppp.c
+++ b/net/l2tp/l2tp_ppp.c
@@ -1862,5 +1862,5 @@
 MODULE_DESCRIPTION("PPP over L2TP over UDP");
 MODULE_LICENSE("GPL");
 MODULE_VERSION(PPPOL2TP_DRV_VERSION);
-MODULE_ALIAS("pppox-proto-" __stringify(PX_PROTO_OL2TP));
+MODULE_ALIAS_NET_PF_PROTO(PF_PPPOX, PX_PROTO_OL2TP);
 MODULE_ALIAS_L2TP_PWTYPE(11);