pinctrl: pinctrl-imx: add imx6q pinctrl driver

Acked-by: Stephen Warren <swarren@wwwdotorg.org>
Acked-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Dong Aisheng <dong.aisheng@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>