Fix a logic error for setting block I/O

Fix a logic error, the initial value of ret = -1, if just set --config,
it will goto endjob directly without doing its really job here.
Signed-off-by: NLei Li <lilei@linux.vnet.ibm.com>

src/qemu/qemu_driver.c

@@ -11233,9 +11233,9 @@ qemuDomainSetBlockIoTune(virDomainPtr dom,
         qemuDomainObjEnterMonitorWithDriver(driver, vm);
         ret = qemuMonitorSetBlockIoThrottle(priv->mon, device, &info);
         qemuDomainObjExitMonitorWithDriver(driver, vm);
+        if (ret < 0)
+            goto endjob;
     }
-    if (ret < 0)
-        goto endjob;
 
     if (flags & VIR_DOMAIN_AFFECT_CONFIG) {
         sa_assert(persistentDef && idx >= 0);