Bluetooth: controller: Fix aux ptr offset calculation for S2 Coded PHY

In the calculation of auxiliary PDU offset for periodic advertising
AUX_CHAIN_IND PDUs there were used old macro that was removed.
The code didn't compile.
Also there were no support for S2 Coded PHY in the offset calculation.

Signed-off-by: Piotr Pryga <piotr.pryga@nordicsemi.no>