re-introduce ipa_ccm_idtag_parse_off()

In the previous commit we deprecated ipa_ccm_idtag_parse() but
also removed ipa_ccm_idtag_parse_off(), for which I couldn't find
any users.  However, legacy openbsc.git still uses this function,
so let's re-introiduce it in its original form.

Change-Id: Ibfe53b04340eb355c8bfb8453a2af1522a4b6baf
diff --git a/include/osmocom/gsm/ipa.h b/include/osmocom/gsm/ipa.h
index ec143d0..93cb1bf 100644
--- a/include/osmocom/gsm/ipa.h
+++ b/include/osmocom/gsm/ipa.h
@@ -28,6 +28,8 @@
 
 int ipa_ccm_idtag_parse(struct tlv_parsed *dec, unsigned char *buf, int len)
 	OSMO_DEPRECATED("Use ipa_ccm_id_{get,resp}_parse instead");
+int ipa_ccm_idtag_parse_off(struct tlv_parsed *dec, unsigned char *buf, int len, const int len_offset)
+	OSMO_DEPRECATED("Use ipa_ccm_id_{get,resp}_parse instead");
 
 /* parse payload of IPA CCM ID GET into a osmocom TLV style representation */
 int ipa_ccm_id_get_parse(struct tlv_parsed *dec, const uint8_t *buf, unsigned int len);
@@ -35,9 +37,6 @@
 /* parse payload of IPA CCM ID RESP into a osmocom TLV style representation */
 int ipa_ccm_id_resp_parse(struct tlv_parsed *dec, const uint8_t *buf, unsigned int len);
 
-/* Is the TAG included in the length field? */
-int ipa_ccm_idtag_parse_off(struct tlv_parsed *dec, unsigned char *buf, int len, const int len_offset);
-
 /* parse an Unit ID in string format into the 'ipaccess_unit' data structure */
 int ipa_parse_unitid(const char *str, struct ipaccess_unit *unit_data);