apparmor: fix af_unix auditing to include all address information

The auditing of addresses currently doesn't include the source address
and mixes source and foreign/peer under the same audit name. Fix this
so source is always addr, and the foreign/peer is peer_addr.

Fixes: c05e7058 ("apparmor: add fine grained af_unix mediation")
Signed-off-by: John Johansen <john.johansen@canonical.com>