Bluetooth: Fix incorrectly disabling page scan when toggling connectable

If we have entries in the whitelist we shouldn't disable page scanning
when disabling connectable mode. This patch adds the necessary check to
the Set Connectable command handler.

Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>