Update to kernel headers v4.12.3.

Test: NA
Change-Id: Iee3d607e8a0fe866ffa1f123308af0713719ea29
diff --git a/original/uapi/linux/mpls_iptunnel.h b/original/uapi/linux/mpls_iptunnel.h
index d80a049..f5e4509 100644
--- a/original/uapi/linux/mpls_iptunnel.h
+++ b/original/uapi/linux/mpls_iptunnel.h
@@ -16,11 +16,13 @@
 /* MPLS tunnel attributes
  * [RTA_ENCAP] = {
  *     [MPLS_IPTUNNEL_DST]
+ *     [MPLS_IPTUNNEL_TTL]
  * }
  */
 enum {
 	MPLS_IPTUNNEL_UNSPEC,
 	MPLS_IPTUNNEL_DST,
+	MPLS_IPTUNNEL_TTL,
 	__MPLS_IPTUNNEL_MAX,
 };
 #define MPLS_IPTUNNEL_MAX (__MPLS_IPTUNNEL_MAX - 1)