The commit 3ab1663af6c1 ("watchdog: stm32_iwdg: Add pretimeout support")Reviewed-by: Marek Vasut <marex@xxxxxxx>
introduces the support for the pre-timeout interrupt.
The support for this interrupt is optional but the driver uses the
platform_get_irq() wich produces an error message during the driver
probe if we don't have any `interrupts` property in the DT.
Use the platform_get_irq_optional() API to get rid of the error message
as this property is optional.
Fixes: 3ab1663af6c1 ("watchdog: stm32_iwdg: Add pretimeout support")
Signed-off-by: Clément Le Goffic <clement.legoffic@xxxxxxxxxxx>