openvswitch: Use regular GRE net_device instead of vport

Using GRE tunnel meta data collection feature, we can implement
OVS GRE vport. This patch removes all of the OVS
specific GRE code and make OVS use a ip_gre net_device.
Minimal GRE vport is kept to handle compatibility with
current userspace application.

Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Acked-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/openvswitch/Kconfig b/net/openvswitch/Kconfig
index 1584040..422dc05 100644
--- a/net/openvswitch/Kconfig
+++ b/net/openvswitch/Kconfig
@@ -34,7 +34,7 @@
 config OPENVSWITCH_GRE
 	tristate "Open vSwitch GRE tunneling support"
 	depends on OPENVSWITCH
-	depends on NET_IPGRE_DEMUX
+	depends on NET_IPGRE
 	default OPENVSWITCH
 	---help---
 	  If you say Y here, then the Open vSwitch will be able create GRE