made L1 DLSCH encoding stateless. harq_pid/round information are not kept in PHY. Full channel encoding is performed for each transmission of a transport block.
Still to be done: test, then cleanup data structures and fix unitary simulations.

mac_remove_nr_ue(): no need to memset sched_ctrl, since it is done on
connection of a UE

the whole UE_sched_ctrl is initialized in add_new_nr_ue(), which will
also init the per-UE HARQ.