As the precedent commit, this commit deals with the realtime problems
that we currently have on the CI bench.

For DL HARQ feedback, nFAPI does not give us the HARQ process ID.
Instead, we have to figure this out "from timing", i.e., if we trigger
PUCCH reception, we will get a message with HARQ if we instructed the
PHY to do so. If we have real-time problems, it seems (I cannot verify:
don't have real time problems) that we do not get the nFAPI message with
HARQ feedback. Thus, we need to skip the HARQ processes that should have
been processed in the past, which happens in this commit.

- No dynamic allocation of PUCCH structures
- Use first PUCCH for HARQ (can only allocate for up to two slots in
  single PUCCH, simplistic nr_acknack_scheduling!)
- Use second PUCCH for CSI, do not multiplex!