usb: hub: PDO: InternalDeviceControl can be called in DPC

As InternalDeviceControl can be called in DPC, we should avoid scanning
of parent's child list because it uses guarded mutex for
synchronization. So here we just adding new checking for safety and
removing isValidPDO() call.

svn path=/branches/GSoC_2016/USB/; revision=72393

Author: mvardan

drivers/usb/usbhub/pdo.c

@@ -210,7 +210,7 @@ USBHUB_PdoHandleInternalDeviceControl(
 
     if (ChildDeviceExtension->Common.PnPState == SurpriseRemovePending ||
         ChildDeviceExtension->Common.PnPState == RemovePending ||
-        !IsValidPDO(DeviceObject))
+        ChildDeviceExtension->ParentDeviceObject == NULL)
     {
         // Parent or child device was surprise removed.
         DPRINT1("[USBHUB] Request for removed device object %p\n", DeviceObject);