gprs_bssgp_rim: add value strings for enum bssgp_nacc_cause

Change-Id: I3354699555569c2b0bd1b4313cffd32a0cbeffe9
Related: SYS#5103
diff --git a/src/gb/libosmogb.map b/src/gb/libosmogb.map
index 763ddc6..dc9df3a 100644
--- a/src/gb/libosmogb.map
+++ b/src/gb/libosmogb.map
@@ -29,6 +29,7 @@
 bssgp_msgb_copy;
 bssgp_msgb_tlli_put;
 bssgp_msgb_ra_put;
+bssgp_nacc_cause_strs;
 bssgp_parse_cell_id;
 bssgp_parse_rim_pdu;
 bssgp_parse_rim_ri;