INT-3522: MQTT XSD: Fix client-factory attr type

JIRA: https://jira.spring.io/browse/INT-3522

Author: stirp

spring-integration-mqtt/src/main/resources/org/springframework/integration/mqtt/config/xml/spring-integration-mqtt-4.1.xsd

@@ -232,7 +232,7 @@
 						override the defaults. Default is DefaultMqttClientFactory.
 					]]></xsd:documentation>
 					<tool:annotation kind="ref">
-						<tool:expected-type type="org.springframework.integration.mqtt.support.MqttMessageConverter" />
+						<tool:expected-type type="org.springframework.integration.mqtt.core.MqttPahoClientFactory" />
 					</tool:annotation>
 				</xsd:appinfo>
 			</xsd:annotation>