hwmon: (max16065) Fix overflows seen when writing limits

Writing large limits resulted in overflows as reported by module tests.

in0_lcrit: Suspected overflow: [max=5538, read 0, written 2147483647]
in0_crit: Suspected overflow: [max=5538, read 0, written 2147483647]
in0_min: Suspected overflow: [max=5538, read 0, written 2147483647]

Fix the problem by clamping prior to multiplications and the use of
DIV_ROUND_CLOSEST, and by using consistent variable types.
Reviewed-by: Tzung-Bi Shih <tzungbi@kernel.org>
Fixes: f5bae264 ("hwmon: Driver for MAX16065 System Manager and compatibles")
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

drivers/hwmon/max16065.c

@@ -114,9 +114,10 @@ static inline int LIMIT_TO_MV(int limit, int range)
 	return limit * range / 256;
 }
 
-static inline int MV_TO_LIMIT(int mv, int range)
+static inline int MV_TO_LIMIT(unsigned long mv, int range)
 {
-	return clamp_val(DIV_ROUND_CLOSEST(mv * 256, range), 0, 255);
+	mv = clamp_val(mv, 0, ULONG_MAX / 256);
+	return DIV_ROUND_CLOSEST(clamp_val(mv * 256, 0, range * 255), range);
 }
 
 static inline int ADC_TO_CURR(int adc, int gain)