Add CC_CAUSE value_string array

Adds a value_string array for GSM 04.08 Call Control
cause values

Change-Id: I296f208581ce2550805f9d96e20f7319e1199023
diff --git a/include/osmocom/gsm/protocol/gsm_04_08.h b/include/osmocom/gsm/protocol/gsm_04_08.h
index 4635014..e218295 100644
--- a/include/osmocom/gsm/protocol/gsm_04_08.h
+++ b/include/osmocom/gsm/protocol/gsm_04_08.h
@@ -1495,6 +1495,10 @@
 	GSM48_CC_CAUSE_INTERWORKING	= 127,
 };
 
+extern const struct value_string gsm48_cc_cause_names[];
+static inline const char *gsm48_cc_cause_name(enum gsm48_cc_cause val)
+{ return get_value_string(gsm48_cc_cause_names, val); }
+
 /* Annex G, GSM specific cause values for mobility management */
 enum gsm48_reject_value {
 	GSM48_REJECT_IMSI_UNKNOWN_IN_HLR	= 2,