x86: pch: Implement get_gpio_base op

Implement get_gpio_base op for bd82x6x, pch7 and pch9 drivers.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>
3 files changed