task_wdt: use correct hardware watchdog channel number
task_wdt: use correct hardware watchdog channel number

The hardware watchdog was always fed with channel ID 0. This is correct
in most cases, but we should still use the actual ID returned from
wdt_install_timeout.

Signed-off-by: Martin Jäger <54669547a225ff20cba8b75a4adca540eef25858@libre.solar>

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