watchdog: octeon: Remove unneeded linux/miscdevice.h include

watchdog/octeon-wdt-main.c does not use any miscdevice so this patch
remove this unnecessary inclusion.

Signed-off-by: Corentin Labbe <clabbe.montjoie@gmail.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>