BTS_Tests: tune back to CCCH/BCCH in TC_sacch_chan_act_ho_[a]sync

Sending L1CTL_DM_REL_REQ does not make the L1 tune back to CCCH/BCCH.
We need to send a L1CTL_FBSB_REQ after releasing a dedicated channel
if we want to establish another one.  This is essential when running
tests using Calypso PHY, and will be required once we have proper
trxcon_fsm implementation [1] merged.

Related: [1] osmocom-bb.git Ifaf63ead9dd180181358e771367b2a686ba159ca
Change-Id: I65fb243a62fc7670b43f467d6b79268cdfb98f36
1 file changed