Add test_dyn_ts_subslots() and call from main(). Update channel_test.ok.
This includes erratic assert to show a bug for TCH/F_PDCH in PDCH mode: the nr
of subslots should be the same as for a normal PDCH, i.e. zero. This will be
adjusted along with the fix in an upcoming commit.
Change-Id: I09685be3fb3ed1ead4577b772a9fbc31967980d1