Bluetooth: Controller: AD data fragment operation review rework

Added define PDU_AC_EXT_AD_DATA_LEN_MAX, maximum AD data
length possible in AUX_ADV_IND when all Common Extended
Header Format fields are populuted.

Updated function description to explain the added ADI and
Aux Ptr fields support in updating the auxiliary PDUs.

Remove the redundant CTE info population code unnecessary
for new chain PDU as a result of AD data overflow.

Signed-off-by: Vinayak Kariappa Chettimada <vich@nordicsemi.no>