Bluetooth: Remove update_scan hci_request dependancy

This removes the remaining calls to HCI_OP_WRITE_SCAN_ENABLE from
hci_request call chains, and converts them to hci_sync calls.

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