hwmon: (lm78) Fix overflow problems seen when writing large temperature limits

commit 1074d683 upstream.

On platforms with sizeof(int) < sizeof(long), writing a temperature
limit larger than MAXINT will result in unpredictable limit values
written to the chip. Avoid auto-conversion from long to int to fix
the problem.

Cc: Axel Lin <axel.lin@ingics.com>
Reviewed-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

drivers/hwmon/lm78.c

@@ -102,7 +102,7 @@ static inline int FAN_FROM_REG(u8 val, int div)
 
 /* TEMP: mC (-128C to +127C)
    REG: 1C/bit, two's complement */
-static inline s8 TEMP_TO_REG(int val)
+static inline s8 TEMP_TO_REG(long val)
 {
 	int nval = SENSORS_LIMIT(val, -128000, 127000) ;
 	return nval<0 ? (nval-500)/1000 : (nval+500)/1000;