Bluetooth: Controller: Fix to use ADI flag in Periodic Adv Enable

Fix implementation to use ADI flag in Periodic Advertising
enable command to add ADI field in Periodic Advertising
PDUs.

Related to commit 6433a6aa ("Bluetooth: Controller:
Add Periodic Advertising ADI support").

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