Convert iwdg_stm32 STM32 Watchdog driver to new API

[galak]

We have a new driver API for watchdog, the old API has been deprecated for several releases now. We need to convert the driver to use the API or remove it.

[galak]

@apodogrocki can you look at update the driver?

[qianfan-Zhao]

I will do it

[apodogrocki]

@qianfan-Zhao I've already started working on that. If you would like you can think of adding window mode to the Independent Watchdog driver. It has never been activated, but can be useful. That probably requires separate PR.

@erwango @galak There is also a question how to provide support for System Window Watchdog. All watchdog devices are named "WATCHDOG_0" at the moment. In case of STM32 can both IWDG & WWDG co-exist in the same time? Or Kconfig.stm32 should contain choice menu to select desired watchdog type?

[qianfan-Zhao]

here is also a question how to provide support for System Window Watchdog. All watchdog devices are named "WATCHDOG_0" at the moment.

Currently the name of watchdog are defined in Kconfig. Based on the comments in #11331 we should remove the Kconfig options and make DT define the name of watchdog.

Others SoC such as NRF has this lines in dts_fixup.h:

#define CONFIG_WDT_0_NAME		DT_NORDIC_NRF_WATCHDOG_40010000_LABEL

If there has 2 watchdogs, such as IWDG and WWDG, i think it OK to define the difference name in DT:

#define CONFIG_WDT_0_NAME DT_STM32_IWDG_XXX_LABEL
#define CONFIG_WDT_1_NAME DT_STM32_WWDG_XXX_LABEL