thermal/drivers/mediatek/lvts_thermal: Return error in case of invalid efuse data

This patch prevents from registering thermal entries and letting the
driver misbehave if efuse data is invalid. A device is not properly
calibrated if the golden temperature is zero.

Fixes: f5f633b18234 ("thermal/drivers/mediatek: Add the Low Voltage Thermal Sensor driver")
Signed-off-by: Julien Panis <jpanis@baylibre.com>
Reviewed-by: Nicolas Pitre <npitre@baylibre.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20240604-mtk-thermal-calib-check-v2-1-8f258254051d@baylibre.com
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

drivers/thermal/mediatek/lvts_thermal.c

diff --git a/drivers/thermal/mediatek/lvts_thermal.c b/drivers/thermal/mediatek/lvts_thermal.c
index 82c355c..819ed01 100644
--- a/drivers/thermal/mediatek/lvts_thermal.c
+++ b/drivers/thermal/mediatek/lvts_thermal.c
@@ -769,7 +769,11 @@ static int lvts_golden_temp_init(struct device *dev, u8 *calib,
 	 */
 	gt = (((u32 *)calib)[0] >> lvts_data->gt_calib_bit_offset) & 0xff;
 
-	if (gt && gt < LVTS_GOLDEN_TEMP_MAX)
+	/* A zero value for gt means that device has invalid efuse data */
+	if (!gt)
+		return -ENODATA;
+
+	if (gt < LVTS_GOLDEN_TEMP_MAX)
 		golden_temp = gt;
 
 	golden_temp_offset = golden_temp * 500 + lvts_data->temp_offset;