drivers: watchdog: Pass timeout in ms if iwdg is started at boot
drivers: watchdog: Pass timeout in ms if iwdg is started at boot

iwdg_stm32_install_timeout expects a timeout passed in
milli seconds. As the timeout is defined in micro
seconds in Kconfig.stm32, we need to divide by
USEC_PER_MSEC when CONFIG_IWDG_START_AT_BOOT is
activated because iwdg_stm32_install_timeout makes
the multiplication by USEC_PER_MSEC.

Fixes #18695

Signed-off-by: Philémon Jaermann <8dd9914e95c1c2b4aa1e9fa87956b512ffc689aa@gmail.com>

finikorg/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,nashif/zephyr,galak/zephyr,Vudentz/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,Vudentz/zephyr,zephyrproject-rtos/zephyr,Vudentz/zephyr,Vudentz/zephyr,Vudentz/zephyr,finikorg/zephyr,galak/zephyr,Vudentz/zephyr,zephyrproject-rtos/zephyr,nashif/zephyr,galak/zephyr,finikorg/zephyr,finikorg/zephyr,finikorg/zephyr,nashif/zephyr,nashif/zephyr,galak/zephyr,nashif/zephyr