drivers:tty:fix up ENOIOCTLCMD error handling

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>