Bluetooth: controller: ULL: ull_adv_sync_hdr_set_clear update PDU in place

Enabling or disabling transmission of Constant Tone Extension with
periodic advertising PDUs requires update of a PDU content.
CTE_INFO field of periodic advertising PDU must be filled with
appropriate data. That operation may be done for periodic
advertising PDU (or chain of PDUs) filled with other payload that
wasn't enqueued towards LLL. In that situation PDUs are updated
in place, to avoid increase of memory consumption.

The commit changes ull_adv_sync_pdu_set_clear function to
make possible update of the advertising PDU in place.

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