USB: use the device lock for persist_enabled

This patch (as1325) changes the locking for the persist_enabled flag
in struct usb_device.  Now it is protected by the device lock, along
with all its neighboring bit flags, instead of the PM lock (which is
about to vanish anyway).
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/core/sysfs.c

@@ -256,9 +256,10 @@ set_persist(struct device *dev, struct device_attribute *attr,
 
 	if (sscanf(buf, "%d", &value) != 1)
 		return -EINVAL;
-	usb_pm_lock(udev);
+
+	usb_lock_device(udev);
 	udev->persist_enabled = !!value;
-	usb_pm_unlock(udev);
+	usb_unlock_device(udev);
 	return count;
 }