bugfix: add PCell to serving_cells in fallback path and refactor update logic
Fix assertion failure in rrc_gNB_send_NGAP_NAS_FIRST_REQ() when RRC
Reestablishment falls back to RRC Setup. The fallback path was not
adding the PCell to the UE's serving_cells array, causing
rrc_get_pcell_for_ue() to return NULL.
Major changes:
- Add rrc_update_ue_pcell() helper function that handles PCell updates
for both new UEs (fallback) and existing UEs (normal reestablishment)
- Refactor normal reestablishment path to use rrc_update_ue_pcell()
helper instead of manual cleanup + add sequence
- Add PCell update to fallback_rrc_setup path using the same helper
- Move C-RNTI validation after current_cell fetch to ensure current_cell
is initialized before fallback_rrc_setup label
- Change error handling: return instead of fallback when PCell add fails
in normal reestablishment path
Fixes CI failure in !3908
Robert Schmidt
2b7f3e2f72