Add driver support for gpio of MT7621 SoC.
Signed-off-by: NSergio Paracuellos <sergio.paracuellos@gmail.com>
Reviewed-by: NNeilBrown <neil@brown.name>
[Switched wording WIDTH to STRIDE]
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>