mfd: lpc_ich: Fix ACPI enable bitmask

The original bitmask of 0x10 was incorrect and would result in a write
to a reserved read-only bit instead of enabling the ACPI I/O
region.  Update it to the proper value of 0x80.

Signed-off-by: Peter Tyser <ptyser@xes-inc.com>
Tested-by: Rajat Jain <rajatjain@juniper.net>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Lee Jones <lee.jones@linaro.org>