Fix update-manager.service ExecStart command (eclipse-kanto#65)

[eclipse-kanto#63] Wrong argument in update manager service unit template

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Signed-off-by: Kristiyan Gostev <kristiyan.gostev@bosch.com>

recipes-management/update-manager/files/service.template

@@ -7,7 +7,7 @@ Requires=mosquitto.service
 
 [Service]
 Type=simple
-ExecStart=@UM_BIN_DD@/update-manager -configFile @UM_CFG_DD@/update-manager/config.json
+ExecStart=@UM_BIN_DD@/update-manager --config-file @UM_CFG_DD@/update-manager/config.json
 Restart=always
 
 [Install]