Return ENOTTY instead of ENOIOCTLCMD in user-visible ioctl() results

The watchdog drivers used to return ENOIOCTLCMD for bad ioctl() commands.
ENOIOCTLCMD should not be visible by the user, so use ENOTTY instead.
Signed-off-by: NSamuel Tardieu <sam@rfc1149.net>
Signed-off-by: NWim Van Sebroeck <wim@iguana.be>
Acked-by: NAlan Cox <alan@redhat.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>