Note: the slots to "enable" depend on the TDD configuration, so instead
of configuring it statically, we should read it from the configuration
file.

This reverts commit bfb12919.

- 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!