gNB: fix MAC TA command scheduling if measurement gaps are configured
In the current implementation, if UE transmission is interrupted via
nr_mac_interrupt_ue_transmission(), UE_sched_ctrl.ta_frame is modified to be
the previous frame avoiding TA scheduling in the measurement gap. So the next
scheduled TA is shifted to be in 99 frames. As there are other measurement gaps
before that, the scheduled TA is always shifted, but actually never reached,
effectively disabling the MAC TA commands.
To fix this, UE_sched_ctrl.ta_frame is changed to not indicate the last TA
command transmission, but the next one. This allows to check in
nr_mac_interrupt_ue_transmission() if the next TA command transmission is within
the measurement gap and if so shift it to just after that gap.
Jaroslava Fiedlerova
122bda995e