ipa: add ipaccess_tlv_to_unitdata()

this function takes the parsed TLVs of an IPA ID RESP message and
fills a 'struct ipaccess_unit'.
diff --git a/include/osmocom/abis/ipa.h b/include/osmocom/abis/ipa.h
index 7030830..17b5f23 100644
--- a/include/osmocom/abis/ipa.h
+++ b/include/osmocom/abis/ipa.h
@@ -95,5 +95,7 @@
 int ipaccess_idtag_parse(struct tlv_parsed *dec, unsigned char *buf, int len);
 int ipaccess_send_id_req(int fd);
 int ipaccess_parse_unitid(const char *str, struct ipaccess_unit *unit_data);
+int ipaccess_tlv_to_unitdata(struct ipaccess_unit *ud,
+			     const struct tlv_parsed *tp);
 
 #endif