bluetooth: Reorganize code to avoid Coverity NULL dereference warning

bluetooth: Reorganize code to avoid Coverity NULL dereference warning

CID 1353122

this is a false-positive because

   if (dbus_message_has_interface(p->message, "org.bluez.Manager") ||
        dbus_message_has_interface(p->message, "org.bluez.Adapter"))
        d = NULL;
    else if (!(d = pa_hashmap_get(y->devices, dbus_message_get_path(p->message)))) {
        pa_log_warn("Received GetProperties() reply from unknown device: %s (device removed?)",
dbus_message_get_path(p->message));
        goto finish2;
    }

d can be NULL only if p->message interface is org.bluez.Manager or
org.bluez.Adapter. If

    dbus_message_is_method_call(p->message, "org.bluez.Device", "GetProperties")

returns true, we know that the interface is org.bluez.Device.

thanks, Tanu!