qnetd: Add note about coverity false positive err

Not too keen to add coverity specific comment as described in
https://community.synopsys.com/s/article/
Suppressing-False-Positive-Intentional-defects but it's handy to have
note in code.

Signed-off-by: Jan Friesse <jfriesse@redhat.com>

qdevices/qnetd-cluster-list.c

@@ -111,6 +111,9 @@ qnetd_cluster_list_add_client(struct qnetd_cluster_list *list, struct qnetd_clie
 	}
 
 	if (entry == NULL) {
+		/*
+		 * Coverity reports false positive var_deref_op error on following line
+		 */
 		TAILQ_INSERT_TAIL(&cluster->client_list, client, cluster_entries);
 	}