Bluetooth: controller: Move scan response data swap outside tIFS

In preparation towards Privacy 1.2, move implementation that
swapped scan response PDU double buffer to same place as
where adv data PDU double buffer is swapped. So that, change
in AdvA in adv data PDU can be reflected in scan response
PDU buffer.

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