Bluetooth: Move Adv Instance timer to hci_sync

The Advertising Instance expiration timer adv_instance_expire was
handled with the deprecated hci_request mechanism, rather than it's
replacement: hci_sync.

Signed-off-by: Brian Gix <brian.gix@intel.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>