* bts: Add tests for CBCH LOAD IND (underflow, overflow)
* bts: Add TC_sms_cb_cmd_sdcch{4,8}_extd_multi
* bts: Test case for mixed NORMAL and DEFAULT SMSCB
* bts: Refactor code to support mixed DEFAULT + NORMAL and EXTENDED CBCH
* bts: Test for removal of CBCH DEFAULT message
* bts: Add TC_sms_cb_cmd_cbch_sdcch{4,8}_default_only
* bts: Add TC_sms_cb_cmd_cbch_sdcch{4,8}_multi()
* bts: CBCH related tests for OsmoBTS