Merge branch 'develop-nb-iot-mac' of https://gitlab.eurecom.fr/oai/openairinterface5g into develop-nb-iot-mac

expected warnings since some variables will be used in future

+ creation of new file: openair1/PHY/LTE_TRANSPORT/uci_tools_NB_IoT.c

+ creation of three new files:
openair1/PHY/LTE_ESTIMATION/freq_equalization_NB_IoT.c
openair1/PHY/LTE_ESTIMATION/lte_ul_channel_estimation_NB_IoT.c
openair1/PHY/LTE_TRANSPORT/ulsch_demodulation_NB_IoT.c

openair1/PHY/CODING/lte_segmentation_NB_IoT.c
openair1/PHY/CODING/viterbi_lte_NB_IoT.c
openair1/PHY/LTE_TRANSPORT/lte_mcs_NB_IoT.c

+ creation of new file :openair2/PHY_INTERFACE/defs_NB_IoT.h
+ additional warnings because of the new MAC_xface_NB_IoT (126 remaining)

creation of two new files: openair1/PHY/LTE_ESTIMATION/defs_NB_IoT.h
openair1/PHY/LTE_ESTIMATION/lte_adjust_sync_NB_IoT.c

openair1/PHY/LTE_TRANSPORT/vars_NB_IoT.h

openair2/RRC/LITE/rrc_eNB_UE_context_NB_IoT.c
openair2/RRC/LITE/rrc_eNB_UE_context_NB_IoT.h