USB: Disable auto-suspend for USB 3.0 hubs.

USB 3.0 devices have a slightly different suspend sequence than USB
2.0/1.1 devices.  There isn't support for USB 3.0 device suspend yet, so
make khubd leave autosuspend disabled for USB 3.0 hubs.  Make sure that
USB 3.0 roothubs still have autosuspend enabled, since that path in the
xHCI driver works fine.
Signed-off-by: NSarah Sharp <sarah.a.sharp@linux.intel.com>

drivers/usb/core/hub.c

@@ -1290,8 +1290,14 @@ static int hub_probe(struct usb_interface *intf, const struct usb_device_id *id)
 	desc = intf->cur_altsetting;
 	hdev = interface_to_usbdev(intf);
 
-	/* Hubs have proper suspend/resume support */
-	usb_enable_autosuspend(hdev);
+	/* Hubs have proper suspend/resume support.  USB 3.0 device suspend is
+	 * different from USB 2.0/1.1 device suspend, and unfortunately we
+	 * don't support it yet.  So leave autosuspend disabled for USB 3.0
+	 * external hubs for now.  Enable autosuspend for USB 3.0 roothubs,
+	 * since that isn't a "real" hub.
+	 */
+	if (!hub_is_superspeed(hdev) || !hdev->parent)
+		usb_enable_autosuspend(hdev);
 
 	if (hdev->level == MAX_TOPO_LEVEL) {
 		dev_err(&intf->dev,