CI: fix a few cppcheck errors

executables/main-fs6.c

openair1/PHY/LTE_TRANSPORT/ulsch_decoding.c

openair1/PHY/NR_TRANSPORT/nr_prach.c

openair1/PHY/NR_TRANSPORT/pucch_rx.c

openair1/PHY/NR_UE_ESTIMATION/nr_dl_channel_estimation.c

openair1/PHY/NR_UE_TRANSPORT/nr_ulsch_ue.c

openair1/SIMULATION/NR_PHY/dlsim.c

openair1/SIMULATION/NR_PHY/prachsim.c

openair1/SIMULATION/NR_PHY/ulsim.c