ASCI: Add Notification/NCH message to gsm_04_08.h

This message is (the only message) used on the NCH to notify the MS
about all currently ongoing voice group/broadcast calls.

Change-Id: Iff1555a2914ce0a1ead6ab883498adb2c33b135e
diff --git a/include/osmocom/gsm/protocol/gsm_04_08.h b/include/osmocom/gsm/protocol/gsm_04_08.h
index 81e4817..a4e05d6 100644
--- a/include/osmocom/gsm/protocol/gsm_04_08.h
+++ b/include/osmocom/gsm/protocol/gsm_04_08.h
@@ -1302,6 +1302,14 @@
 	uint8_t rest[0];
 } __attribute__ ((packed));
 
+/* Section 9.1.21b */
+struct gsm48_notification_nch {
+	uint8_t l2_plen;
+	uint8_t proto_discr;
+	uint8_t msg_type;
+	uint8_t data[0];
+} __attribute__((packed));
+
 /* Section 9.1.22 */
 struct gsm48_paging1 {
 #if OSMO_IS_LITTLE_ENDIAN