thermal: exynos: Propagate error value from tmu_read()

tmu_read() in case of Exynos4210 might return error for out of bound
values. Current code ignores such value, what leads to reporting critical
temperature value. Add proper error code propagation to exynos_get_temp()
function.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
CC: stable@vger.kernel.org # v4.6+
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>

drivers/thermal/samsung/exynos_tmu.c

@@ -892,19 +892,24 @@ static void exynos7_tmu_control(struct platform_device *pdev, bool on)
 static int exynos_get_temp(void *p, int *temp)
 {
 	struct exynos_tmu_data *data = p;
+	int value, ret = 0;
 
 	if (!data || !data->tmu_read || !data->enabled)
 		return -EINVAL;
 
 	mutex_lock(&data->lock);
 	clk_enable(data->clk);
 
-	*temp = code_to_temp(data, data->tmu_read(data)) * MCELSIUS;
+	value = data->tmu_read(data);
+	if (value < 0)
+		ret = value;
+	else
+		*temp = code_to_temp(data, value) * MCELSIUS;
 
 	clk_disable(data->clk);
 	mutex_unlock(&data->lock);
 
-	return 0;
+	return ret;
 }
 
 #ifdef CONFIG_THERMAL_EMULATION