Changes

bts: add TC_data_facch_*: test FACCH/[FH] on data channels

So far we have been testing the actual traffic of TCH/[FH] in data
mode (CSD), but not FACCH/[FH].  Add separate testcases for that.

Half-rate variants of the new testcases crash osmo-bts-trx, so
comment them out in the control section until the problem is fixed.

Change-Id: I2098ccd651fc2a81f62e70be64af386ab0ca6148
Related: OS#6618