mosquitto_2.0.10.bb: remove dlt-daemon default dependency

dlt-daemon should only be a dependency if the PACKAGECONFIG is selected.
This is actually handled by PACKAGECONFIG[dlt] directly and thus the
default DEPEND on it is superfluous.

Removing it fixes the situation where dlt is disabled for mosquitto.

Signed-off-by: Stefan Schmidt <stefan.schmidt@huawei.com>