hwmon: (ds620) Fix handling of negative temperatures

Signed (negative) temperatures were not handled correctly.
Signed-off-by: NRoland Stigge <stigge@antcom.de>
Signed-off-by: NGuenter Roeck <guenter.roeck@ericsson.com>
Cc: stable@kernel.org # v2.6.38+

drivers/hwmon/ds620.c

@@ -72,7 +72,7 @@ struct ds620_data {
 	char valid;		/* !=0 if following fields are valid */
 	unsigned long last_updated;	/* In jiffies */
 
-	u16 temp[3];		/* Register values, word */
+	s16 temp[3];		/* Register values, word */
 };
 
 /*