watchdog: aspeed: Enable pre-timeout interrupt

Enable the core pre-timeout interrupt on AST2500 and AST2600.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20221101205338.577427-2-eajames@linux.ibm.com


Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>