pinctrl: berlin: add the berlin4ct pinctrl driver

Add the pin-controller driver for Marvell Berlin BG4CT SoC, with definition
of its groups and functions. This uses the core Berlin pinctrl driver.

Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
Acked-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Acked-by: Antoine Tenart <antoine.tenart@free-electrons.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>