Bluetooth: Fix updating scan mode in set_bredr()

Now that the connectable setting is also applicable for the LE side it's
possible that the HCI_CONNECTABLE flag is already set when changing the
BR/EDR setting from false to true while the controller is powered. In
this situation we need to update the BR/EDR scan mode to reflect the
setting. Additionally, since HCI_CONNECTABLE also applies to LE we must
not clear the HCI_CONNECTABLE flag when disabling bredr.

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