ARM: mvebu: Add pinctrl support to Armada 370 SoC

This commits adds the necessary device tree information to define the
compatible property for the pinctrl driver instance of Armada 370 SoC.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Tested-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Reviewed-by: Stephen Warren <swarren@wwwdotorg.org>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>