This requires some updates to the nFAPI code as well.
We also have declared the def_dci_rel15 extern variable
consistently throughout the code.

In this commit, the gNB is still crashing. However, it seems
that the NSA UE is sending the proper responses back, but there
some sort of incorrect management of the def_dci_pdu_rel15
variable. If we memset this array to 0, we can see incorrect
0 assignments to elements of the UCI indications. Hopefully
fixing this issue will result in less gNB crashes.