drivers/watchdog: wwdg_stm32: Check return value of clock_control_on

In function wwdg_stm32_init, return value of clock_control_on
was not checked.
This is reported as an issue by coverity (CID 219600).
Fix this.

Fixes #33067

Signed-off-by: Erwan Gouriou <erwan.gouriou@linaro.org>

drivers/watchdog/wdt_wwdg_stm32.c

@@ -251,11 +251,9 @@ static int wwdg_stm32_init(const struct device *dev)
 	const struct device *clk = DEVICE_DT_GET(STM32_CLOCK_CONTROL_NODE);
 	const struct wwdg_stm32_config *cfg = WWDG_STM32_CFG(dev);
 
-	clock_control_on(clk, (clock_control_subsys_t *) &cfg->pclken);
-
 	wwdg_stm32_irq_config(dev);
 
-	return 0;
+	return clock_control_on(clk, (clock_control_subsys_t *) &cfg->pclken);
 }
 
 static struct wwdg_stm32_data wwdg_stm32_dev_data = {