drivers:tty:fix up ENOIOCTLCMD error handling

At commit 07d106d, 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>

drivers/tty/tty_io.c

@@ -2774,7 +2774,7 @@ long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 	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;