Prevent triggering N2 handover when the UE has no active PDU session
by adding an early check in nr_rrc_trigger_n2_ho(), so we avoid building
an invalid HO Required. This aligns with 3GPP TS 38.413 (§9.2.3.1), where
HANDOVER REQUIRED carries a PDU Session Resource List with at least one
PDU Session Resource Item (range 1..maxnoofPDUSessions).
Fix a UE crash in the neighbor-measurement task setup by allocating the per-antenna
rxdata pointer array before indexing it in pbch_processing(), and freeing it in
nr_ue_meas_neighboring_cell() after measurements complete.
The crash is triggered by intra-frequency neighbor measurements.
Guido Casati