hwmon: (nct7802) fix visibility of temp3

Excerpt from datasheet:
7.2.32 Mode Selection Register
RTD3_MD : 00=Closed , 01=Reserved , 10=Thermistor mode , 11=Voltage sense

Show temp3 only in Thermistor mode

Cc: stable@vger.kernel.org # v3.19+
Signed-off-by: Constantine Shulyupin <const@MakeLinux.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

drivers/hwmon/nct7802.c

@@ -547,7 +547,7 @@ static umode_t nct7802_temp_is_visible(struct kobject *kobj,
 	if (index >= 9 && index < 18 &&
 	    (reg & 0x0c) != 0x04 && (reg & 0x0c) != 0x08)	/* RD2 */
 		return 0;
-	if (index >= 18 && index < 27 && (reg & 0x30) != 0x10)	/* RD3 */
+	if (index >= 18 && index < 27 && (reg & 0x30) != 0x20)	/* RD3 */
 		return 0;
 	if (index >= 27 && index < 35)				/* local */
 		return attr->mode;