hwmon: (it87) Preserve configuration register bits on init

We were accidentally losing one bit in the configuration register on
device initialization. It was reported to freeze one specific system
right away. Properly preserve all bits we don't explicitly want to
change in order to prevent that.
Reported-by: NStevie Trujillo <stevie.trujillo@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: NJean Delvare <khali@linux-fr.org>
Reviewed-by: NGuenter Roeck <linux@roeck-us.net>

drivers/hwmon/it87.c

@@ -2341,7 +2341,7 @@ static void __devinit it87_init_device(struct platform_device *pdev)
 
 	/* Start monitoring */
 	it87_write_value(data, IT87_REG_CONFIG,
-			 (it87_read_value(data, IT87_REG_CONFIG) & 0x36)
+			 (it87_read_value(data, IT87_REG_CONFIG) & 0x3e)
 			 | (update_vbat ? 0x41 : 0x01));
 }