[WATCHDOG] use ENOTTY instead of ENOIOCTLCMD in ioctl()

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: Samuel Tardieu <sam@rfc1149.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Acked-by: Alan Cox <alan@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>

drivers/char/watchdog/softdog.c

@@ -203,7 +203,7 @@ static int softdog_ioctl(struct inode *inode, struct file *file,
 	};
 	switch (cmd) {
 		default:
-			return -ENOIOCTLCMD;
+			return -ENOTTY;
 		case WDIOC_GETSUPPORT:
 			return copy_to_user(argp, &ident,
 				sizeof(ident)) ? -EFAULT : 0;