Bluetooth: Disable auto-connection parameters when unpairing

For connection parameters that are left around until a disconnection
we should at least clear any auto-connection properties. This way a
new Add Device call is required to re-set them after calling Unpair
Device.

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