ARM: pxa: remove cpu_is_xxx in gpio driver

Avoid to use cpu_is_xxx() in pxa gpio driver. Use platform_device_id
to identify the difference.

Signed-off-by: Haojian Zhuang <haojian.zhuang@linaro.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>