Calling gsm48_cc_tx_release() before mncc_release_ind() has a side
effect: the former may change CC state to GSM_CSTATE_RELEASE_REQ.
This makes the later send MNCC_REL_CNF instead of MNCC_REL_IND, so
if one of the call leg disconnects due to RF failure, the other one
will not be terminated correctly.
Makes both TC_{mo,mt}_call_clear_request TTCN-3 test cases pass.
Change-Id: I3ad4a99757878de3796027325627c87d9a4e93f1
Related: Id16969fe0de04445d1320a96d35cf1d48cc8cf09
Related: SYS#5340