CLOUDSTACK-8128. VM with Datadisk fails to start when storage is put into maintenance.

While migrating a volume from primary to seocndary use a worker VM to perform the operations if the VM associated with the volume is stopped.

plugins/hypervisors/vmware/src/com/cloud/storage/resource/VmwareStorageProcessor.java

@@ -610,7 +610,7 @@ public class VmwareStorageProcessor implements StorageProcessor {
             }
 
             vmMo = hyperHost.findVmOnHyperHost(vmName);
-            if (vmMo == null) {
+            if (vmMo == null || VmwareResource.getVmState(vmMo) == PowerState.PowerOff) {
                 // create a dummy worker vm for attaching the volume
                 DatastoreMO dsMo = new DatastoreMO(hyperHost.getContext(), morDs);
                 workerVm = HypervisorHostHelper.createWorkerVM(hyperHost, dsMo, workerVmName);