This commit also removed MAX_NUM_NEIGH_CELLs and
replaced it with MAX_GNB_CELLS. This was a minor change
OAI added. The standalone sockets for the NR UE correctly
connect to the proxy. We are currently receiving dl_tti
messages from the proxy.

This commit removed all the linking errors
between the NR UE and the LTE UE. This was done by
changing:
-      rrc_data_req_ue
+      rrc_data_req_nr_ue

This commit is not currently building, but I wanted
to be able to save the changes that I have added.

For some reason the htons invocation got deleted which broke
the VNF P7 interface.

Also fixed some build issues, not sure how these got onto the
develop branch to begin with.

- skipping RA procedures when MAC is disabled
- added mac_enabled flag that allows to disable RA and TA at UE from CL

- moved configuration of UE parameters to set_options function
- removed redundant loop over CCs

- removed redundant initialisation of variables
- introduced two "RF helpers" function that are replacing shared code in the sync routines
- added a new .c file and updated the cmakelists and .h files

- got rid of global variable fp
- code cleanup, removed redundant and unused code
- removed unused command line options and variables
- grouped command line setting in set_options function

- this reflects the implementation of IF and IF offset in the gNB RU
- the RF frequencies are set at HW level while the target frequencies are
  stored in fp, therefore the values stored in fp should not be changed
  after sync as only the tx/rx freq is updated
- removed overwritten dl/ul carrier frequencies in fp after sync
- removed redundant set of tx/rx freq in ue_synch (done in init_openair0)
- removed irrelevant set of dl/ul carrier freq in get_options

This commit contains work done by Eurecom and by Benetel.

implementation of missing symbol-based rotation for NR modulation/demodulation (Section 5.3 38.211). Tested with unitary simulators (ulsim/dlsim).
To be tested with gNB testbench and rfsimlator