personmodel: fix incorrect warning message

PeerProfileCollection's name is "Peer profiles" not "ppc"

Change-Id: I3ad0f400c01b404161f87df6f7288baadd4c4ce8
Reviewed-by: Philippe Gorley <philippe.gorley@savoirfairelinux.com>

src/personmodel.cpp

@@ -350,7 +350,7 @@ bool PersonModel::addPeerProfile(Person* person)
 
    // check if this person is saved in the PeerProfileCollection, "ppc"
    if (person->collection() != &TransitionalPersonBackend::instance() and
-       person->collection()->name() != "ppc")
+       person->collection()->id() != "ppc")
    {
       qWarning() << "About to add Person to the PeerProfileCollection which is part of another collection";
    }