At commit 
07d106d0, Linus pointed out that ENOIOCTLCMD should be
translated as ENOTTY to user mode.
For example:
	fd = open("/dev/tty", O_RDWR);
	ioctl(fd, -1, &argp);
then the errno should be ENOTTY but not EINVAL.
Signed-off-by: Wanlong Gao <gaowanlong@cn.fujitsu.com>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
        if (ld->ops->ioctl) {
                retval = ld->ops->ioctl(tty, file, cmd, arg);
                if (retval == -ENOIOCTLCMD)
-                       retval = -EINVAL;
+                       retval = -ENOTTY;
        }
        tty_ldisc_deref(ld);
        return retval;