gpio: pca953x: Add Exar XRA1202

Add Exar XRA1202 8-bit GPIO expander to supported list.

Signed-off-by: Aaron Sierra <asierra@xes-inc.com>
Acked-by: Graeme Smecher <gsmecher@threespeedlogic.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>