Changes

epdg: fix a DTE in as_GSUP_rx_CL_REQ

Recent commit 51490419 uncovered a problem of passing 'dom := *'
to tr_GSUP_CL_REQ, which calls f_gen_tr_ies(), which in its turn
does not properly handle the '*' template kind:

'''
  Dynamic test case error: Restriction `present' on template
                           of type @GSUP_Types.GSUP_CnDomain violated.
'''

The old code was basically equivalent of passing 'dom := ?',
i.e. expecting the OSMO_GSUP_CN_DOMAIN_IE to be present.

Work the problem around by having two alternatives:

* GSUP.receive(tr_GSUP_CL_REQ(dom := omit)
* GSUP.receive(tr_GSUP_CL_REQ(dom := ?)

This patch makes TC_hss_initiated_deregister_permanent_termination pass.

Change-Id: I26738c8c2a0a4b9066bfb619149cbdbaf3e3b5e1
Related: 51490419 ("library/gsup: improve GSUP_IE templates")