gsmtap.h: Introduce new GSMTAP type for LTE NAS messages

Change-Id: I6e1274f17e2d9d2eee16481940642216ca96e3e3
diff --git a/include/osmocom/core/gsmtap.h b/include/osmocom/core/gsmtap.h
index c226185..7a14ba9 100644
--- a/include/osmocom/core/gsmtap.h
+++ b/include/osmocom/core/gsmtap.h
@@ -47,6 +47,7 @@
 #define GSMTAP_TYPE_LTE_MAC_FRAMED	0x0f	/* LTE MAC with context hdr */
 #define GSMTAP_TYPE_OSMOCORE_LOG	0x10	/* libosmocore logging */
 #define GSMTAP_TYPE_QC_DIAG		0x11	/* Qualcomm DIAG frame */
+#define GSMTAP_TYPE_LTE_NAS		0x12	/* LTE Non-Access Stratum */
 
 /* ====== DO NOT MAKE UNAPPROVED MODIFICATIONS HERE ===== */