gpio: add driver for MEN 16Z127 GPIO controller

The 16Z127 is a 32bit GPIO controller on a MCB FPGA.
Every single line can be configured as input and output.

Push pull and open drain are supported as well as setting
a debounce value for the input lines.

Signed-off-by: Andreas Werner <andy@wernerandy.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>