hwmon: (jc42) Use sign_extend32 for sign extension

Despite the name, sign_extend32 works just fine for 16 bit variables,
so it is safe to use.

Cc: Martin Kepplinger <martink@posteo.de>
Reviewed-by: Jean Delvare <jdelvare@suse.de>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

drivers/hwmon/jc42.c

@@ -213,11 +213,7 @@ static u16 jc42_temp_to_reg(int temp, bool extended)
 
 static int jc42_temp_from_reg(s16 reg)
 {
-	reg &= 0x1fff;
-
-	/* sign extend register */
-	if (reg & 0x1000)
-		reg |= 0xf000;
+	reg = sign_extend32(reg, 12);
 
 	/* convert from 0.0625 to 0.001 resolution */
 	return reg * 125 / 2;