hwmon: (tmp421) Fix temperature conversions

commit a44908d7 upstream.

The low bits of temperature registers are status bits, they must be
masked out before converting the register values to temperatures.
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Tested-by: Andre Prendel <andre.prendel@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/hwmon/tmp421.c

@@ -81,14 +81,16 @@ struct tmp421_data {
 
 static int temp_from_s16(s16 reg)
 {
-	int temp = reg;
+	/* Mask out status bits */
+	int temp = reg & ~0xf;
 
 	return (temp * 1000 + 128) / 256;
 }
 
 static int temp_from_u16(u16 reg)
 {
-	int temp = reg;
+	/* Mask out status bits */
+	int temp = reg & ~0xf;
 
 	/* Add offset for extended temperature range. */
 	temp -= 64 * 256;