abis: add attribute names

Add human-readable names for Attributes from 3GPP TS 52.021 ยง9.4

Change-Id: I861247c01557dac7e484ef6fb9b170f69c8a7f55
Related: OS#1614
diff --git a/src/gsm/libosmogsm.map b/src/gsm/libosmogsm.map
index 4a33c46..cd4c0ab 100644
--- a/src/gsm/libosmogsm.map
+++ b/src/gsm/libosmogsm.map
@@ -29,6 +29,7 @@
 abis_nm_ipa_magic;
 abis_mm_event_cause_names;
 abis_nm_pcause_type_names;
+abis_nm_att_names;
 
 osmo_sitype_strs;
 osmo_c4;