gpio: Add Fujitsu MB86S7x GPIO driver

Driver for Fujitsu MB86S7x SoCs that have a memory mapped GPIO controller.

Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>
Signed-off-by: Andy Green <andy.green@linaro.org>
Signed-off-by: Vincent Yang <Vincent.Yang@tw.fujitsu.com>
Signed-off-by: Tetsuya Nuriya <nuriya.tetsuya@jp.fujitsu.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>