[gsm0408] Add enum values for the LOCATION UPDATING REJECT cause

Convert spec to the enum
diff --git a/include/openbsc/gsm_04_08.h b/include/openbsc/gsm_04_08.h
index 24cfd6c..424d4aa 100644
--- a/include/openbsc/gsm_04_08.h
+++ b/include/openbsc/gsm_04_08.h
@@ -337,6 +337,41 @@
 	GSM48_CAUSE_LOC_NET_BEYOND	= 0x0a,
 };
 
+/* Annex G, GSM specific cause values for mobility management */
+enum gsm48_reject_value {
+	GSM48_REJECT_IMSI_UNKNOWN_IN_HLR	= 2,
+	GSM48_REJECT_ILLEGAL_MS			= 3,
+	GSM48_REJECT_IMSI_UNKNOWN_IN_VLR	= 4,
+	GSM48_REJECT_IMEI_NOT_ACCEPTED		= 5,
+	GSM48_REJECT_ILLEGAL_ME			= 6,
+	GSM48_REJECT_PLMN_NOT_ALLOWED		= 11,
+	GSM48_REJECT_LOC_NOT_ALLOWED		= 12,
+	GSM48_REJECT_ROAMING_NOT_ALLOWED	= 13,
+	GSM48_REJECT_NETWORK_FAILURE		= 17,
+	GSM48_REJECT_CONGESTION			= 22,
+	GSM48_REJECT_SRV_OPT_NOT_SUPPORTED	= 32,
+	GSM48_REJECT_RQD_SRV_OPT_NOT_SUPPORTED	= 33,
+	GSM48_REJECT_SRV_OPT_TMP_OUT_OF_ORDER	= 34,
+	GSM48_REJECT_CALL_CAN_NOT_BE_IDENTIFIED	= 38,
+	GSM48_REJECT_INCORRECT_MESSAGE		= 95,
+	GSM48_REJECT_INVALID_MANDANTORY_INF	= 96,
+	GSM48_REJECT_MSG_TYPE_NOT_IMPLEMENTED	= 97,
+	GSM48_REJECT_MSG_TYPE_NOT_COMPATIBLE	= 98,
+	GSM48_REJECT_INF_ELEME_NOT_IMPLEMENTED	= 99,
+	GSM48_REJECT_CONDTIONAL_IE_ERROR	= 100,
+	GSM48_REJECT_MSG_NOT_COMPATIBLE		= 101,
+	GSM48_REJECT_PROTOCOL_ERROR		= 111,
+
+	/* according to G.6 Additional cause codes for GMM */
+	GSM48_REJECT_GPRS_NOT_ALLOWED		= 7,
+	GSM48_REJECT_SERVICES_NOT_ALLOWED	= 8,
+	GSM48_REJECT_MS_IDENTITY_NOT_DERVIVABLE = 9,
+	GSM48_REJECT_IMPLICITLY_DETACHED	= 10,
+	GSM48_REJECT_GPRS_NOT_ALLOWED_IN_PLMN	= 14,
+	GSM48_REJECT_MSC_TMP_NOT_REACHABLE	= 16,
+};
+
+
 struct msgb;
 struct gsm_bts;