gpio: f7188x: Add F71889A GPIO support.

Add F71889A GPIO support.

Fintek F71889A is a SuperIO. It contains HWMON/GPIO/Serial Ports.

Datasheet:
http://www.alldatasheet.com/datasheet-pdf/pdf/459076/FINTEK/F71889A.html

Its virtually identical to the F71889F superio as far as gpios go.
One oddity is GPIO2 at index 0xD0; the datasheet only lists gpio's 7-5,
but it logically seems that it should continue down to 0. I'm not sure
if the driver can handle gpios that are shifted away from index 0 as it
currently stands.

Signed-off-by: Marty Plummer <netz.kernel@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>