Add support for SGSN role via IFLA_GTP_ROLE

This patch corresponds to a Linux kernel patch extending the kernel GTP
to also cover the SGSN role, not just the GGSN role.  In order to keep
the API/behavior compatible, gtp_dev_create() will continue to create
GGSN-side tunnels, while a new gtp_dev_create_sgsn() is introduced to
create SGSN-side tunnels.

Signed-off-by: Harald Welte <laforge@gnumonks.org>
diff --git a/include/linux/if_link.h b/include/linux/if_link.h
index a3f53c9..c66ebbd 100644
--- a/include/linux/if_link.h
+++ b/include/linux/if_link.h
@@ -518,11 +518,18 @@
 #define IFLA_GENEVE_MAX	(__IFLA_GENEVE_MAX - 1)
 
 /* GTP section */
+
+enum ifla_gtp_role {
+	GTP_ROLE_GGSN = 0,
+	GTP_ROLE_SGSN,
+};
+
 enum {
 	IFLA_GTP_UNSPEC,
 	IFLA_GTP_FD0,
 	IFLA_GTP_FD1,
 	IFLA_GTP_PDP_HASHSIZE,
+	IFLA_GTP_ROLE,
 	__IFLA_GTP_MAX,
 };
 #define IFLA_GTP_MAX (__IFLA_GTP_MAX - 1)