hwmon: (drivetemp) Return -ENODATA for invalid temperatures

Holger Hoffstätte observed that Samsung 850 Pro may return invalid
temperatures for a short period of time after resume. Return -ENODATA
to userspace if this is observed.

Fixes:  5b46903d ("hwmon: Driver for disk and solid state drives with temperature sensors")
Reported-by: Holger Hoffstätte <holger@applied-asynchrony.com>
Cc: Holger Hoffstätte <holger@applied-asynchrony.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

drivers/hwmon/drivetemp.c

@@ -264,12 +264,18 @@ static int drivetemp_get_scttemp(struct drivetemp_data *st, u32 attr, long *val)
 		return err;
 	switch (attr) {
 	case hwmon_temp_input:
+		if (!temp_is_valid(buf[SCT_STATUS_TEMP]))
+			return -ENODATA;
 		*val = temp_from_sct(buf[SCT_STATUS_TEMP]);
 		break;
 	case hwmon_temp_lowest:
+		if (!temp_is_valid(buf[SCT_STATUS_TEMP_LOWEST]))
+			return -ENODATA;
 		*val = temp_from_sct(buf[SCT_STATUS_TEMP_LOWEST]);
 		break;
 	case hwmon_temp_highest:
+		if (!temp_is_valid(buf[SCT_STATUS_TEMP_HIGHEST]))
+			return -ENODATA;
 		*val = temp_from_sct(buf[SCT_STATUS_TEMP_HIGHEST]);
 		break;
 	default: