Use a "future" UL_tti_req structure to save in between scheduling and
reception slots. Should also work for FDD.

MR968: Bugfix nr ldpc size typo
- fix the copy of the decoded data bytes at the end of the processing of an LDPC segment 
 
MR962: Remove x2 gnb hardcoding
- Removes hardcoding of some x2 configuration parameters used in ENDC setup request message at gNB side  

MR949: rlc v2: change time keeping
- RLC has timers. We need to keep track of time. 
We introduce rlc_tick() and call it in eNB_dlsch_ulsch_scheduler, which is called every subframe, both in FDD and TDD.