BSC_Tests: fix early mtc.stop in TC_chan_rel_rr_cause()

Calling f_shutdown_helper() in f_tc_chan_rel_rr_cause() leads to
premature test case termination, so only one out of 6 cause values
gets checked.  Move it to TC_chan_rel_rr_cause().

Change-Id: Ic7df15b496fc0750e4f694b1ae79398216f498a7
1 file changed