abis_nm: Some more fall-out from the abis_nm move to libosmocore

we want get_string_value(), not the equivalent of get_value_string()
diff --git a/openbsc/src/libbsc/abis_nm.c b/openbsc/src/libbsc/abis_nm.c
index c47695e..5bcc985 100644
--- a/openbsc/src/libbsc/abis_nm.c
+++ b/openbsc/src/libbsc/abis_nm.c
@@ -380,7 +380,8 @@
 	if (TLVP_PRESENT(&tp, NM_ATT_ADM_STATE)) {
 		new_state.administrative = *TLVP_VAL(&tp, NM_ATT_ADM_STATE);
 		DEBUGPC(DNM, "ADM=%2s ",
-			abis_nm_adm_state_name(new_state.administrative));
+			get_value_string(abis_nm_adm_state_names,
+					 new_state.administrative));
 	}
 	DEBUGPC(DNM, "\n");