usb.h: fix ioctl kernel-doc info

Fix struct field name, prevent kernel-doc warnings.

Warning(include/linux/usb.h:865): No description found for parameter 'unlocked_ioctl'
Warning(include/linux/usb.h:865): Excess struct/union/enum/typedef member 'ioctl' description in 'usb_driver'
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

include/linux/usb.h

@@ -797,7 +797,7 @@ struct usbdrv_wrap {
  * @disconnect: Called when the interface is no longer accessible, usually
  *	because its device has been (or is being) disconnected or the
  *	driver module is being unloaded.
- * @ioctl: Used for drivers that want to talk to userspace through
+ * @unlocked_ioctl: Used for drivers that want to talk to userspace through
  *	the "usbfs" filesystem.  This lets devices provide ways to
  *	expose information to user space regardless of where they
  *	do (or don't) show up otherwise in the filesystem.