Merge branch 'NR_CSI_reporting' of https://gitlab.eurecom.fr/oai/openairinterface5g into NR_CSI_reporting

MR 896 : Nsa remove band hardcodings  
Removes hardcodings of EUTRA and NR bands in UE_Capability_Enquiry and NR_UE Capability_Enquiry messages, providing them from the eNB config file and gNB over X2 respectively. Moreover, the SSB Absolute frequency of the gNB is now provided by the eNB configuration file (instead of being hardcoded at rrc_eNB.c)  

MR903 : pusch ta update  
Update of PUSCH Timing advance  

MR 900 : improve x2/rrc for ENDC  
This MR introduces several enhancements in X2AP and RRC to deal with ENDC. 
The main goal is to deal with UE's on/off and with various errors.
Includes :
- DC prep and DC overall X2 timers
- X2 messages for UE release and DC timers' timeout

Merge branch 'nsa_remove_band_hardcodings' of https://gitlab.eurecom.fr/oai/openairinterface5g into nsa_remove_band_hardcodings

Maybe not the right way to do.
To be checked.

After the UE disconnects, the next connection fails
because the gNB cannot decode Msg3. The root cause
seems to be this ul_valid_re_per_slot not set to 0.
Setting it before the test fixes the problem and
does not seem to impact anything else.