ipa: Introduce helpers to encode IPA CCM ID RESPONSE

The ipa.c file already contained code to parse an ID RESPONSE into the
'struct ipaccess_unit', but it didn't so far contain code to put
together an ID RESPONSE packet based on that structure.  Let's change
that with ipa_ccm_make_id_resp() and a helper wrapper
ipa_ccm_make_id_resp_from_req().

Change-Id: Icbcd8827a75fd5f3393351c1ca372de85275ad35
diff --git a/src/gsm/libosmogsm.map b/src/gsm/libosmogsm.map
index c825dd5..3ac37e1 100644
--- a/src/gsm/libosmogsm.map
+++ b/src/gsm/libosmogsm.map
@@ -378,6 +378,8 @@
 ipa_ccm_idtag_name;
 ipa_ccm_idtag_parse;
 ipa_ccm_idtag_parse_off;
+ipa_ccm_make_id_resp;
+ipa_ccm_make_id_resp_from_req;
 ipa_msg_alloc;
 ipa_msg_recv;
 ipa_msg_recv_buffered;