gsm0408: Completing GSM 04.08 RR message types

- Add missing message types to be up to date with the
  latest specification release (3GPP TS 04.18)

- Add value strings to translate RR message type identifiers
  into human readable strings. (see gsm48_rr_msg_name() in
  gsm48.h

Change-Id: I3ceb070bf4dc8f5a071a5d43c6aa2d4e84c2dec6
diff --git a/include/osmocom/gsm/gsm48.h b/include/osmocom/gsm/gsm48.h
index d6e58c2..6a52c2d 100644
--- a/include/osmocom/gsm/gsm48.h
+++ b/include/osmocom/gsm/gsm48.h
@@ -20,6 +20,7 @@
 extern const struct tlv_definition gsm48_mm_att_tlvdef;
 const char *gsm48_cc_state_name(uint8_t state);
 const char *gsm48_cc_msg_name(uint8_t msgtype);
+const char *gsm48_rr_msg_name(uint8_t msgtype);
 const char *rr_cause_name(uint8_t cause);
 
 int gsm48_decode_lai(struct gsm48_loc_area_id *lai, uint16_t *mcc,