hwmon: (it87) Preserve configuration register bits on init

commit 41002f8d upstream.

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: Stevie Trujillo <stevie.trujillo@gmail.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

drivers/hwmon/it87.c

@@ -2086,7 +2086,7 @@ 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));
 }