Bluetooth: Ensure hci_conn always contains the local identity address

To be consistent with the remote address info in hci_conn we want it to
also contain the local identity address information. This patch updates
the code to copy the right values in place whenever an LE connection has
been established.

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