ARM: berlin: move pinctrl to simple-mfd nodes

Now with proper support for simple-mfd probed pinctrl driver, move
to the new soc-pinctrl and system-pinctrl nodes.

Signed-off-by: Antoine Tenart <antoine.tenart@free-electrons.com>
Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>