msc: allow another reject cause in TC_cm_reest_req_reject

osmo-msc will soon have CM Re-Establishing support, and it will start
returning a different reject code instead of
GSM48_REJECT_SRV_OPT_NOT_SUPPORTED. In TC_cm_reest_req_reject, there is
no previous ongoing connection let alone a voice call, so osmo-msc will
return GSM48_REJECT_CALL_CAN_NOT_BE_IDENTIFIED.

Related: SYS#5130
Change-Id: I3eebab2b26016fb0ef7bf958208eaba6ae4c7836
1 file changed