Bluetooth: Store source address of HCI connections

The source addressed was based on the public address of the HCI device,
but with LE connections this not always the case. For example single
mode LE-only controllers would use a static random address. And this
address is configured by userspace.

To not complicate the lookup of what kind of address is in use, store
the correct source address for each HCI connection.

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