watchdog: iTCO_wdt: Using existing macro define covers more scenarios

For power management, SET_NOIRQ_SYSTEM_SLEEP_PM_OPS defined for
CONFIG_PM_SLEEP, will point ->suspend_noirq, ->freeze_noirq and
->poweroff_noirq to the same function. Vice versa happens for
->resume_noirq, ->thaw_noirq and ->restore_noirq.

Signed-off-by: Liu Xinpeng <liuxp11@chinatelecom.cn>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/1650967905-3199-1-git-send-email-liuxp11@chinatelecom.cn
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>