* Pin-controller driver for the Marvell Berlin SoCs

Pin control registers are part of both chip controller and system
controller register sets. Pin controller nodes should be a sub-node of
either the chip controller or system controller node. The pins
controlled are organized in groups, so no actual pin information is
needed.

A pin-controller node should contain subnodes representing the pin group
configurations, one per function. Each subnode has the group name and
the muxing function used.

Be aware the Marvell Berlin datasheets use the keyword 'mode' for what
is called a 'function' in the pin-controller subsystem.

Required properties:
- compatible: should be one of:
	"marvell,berlin2-soc-pinctrl",
	"marvell,berlin2-system-pinctrl",
	"marvell,berlin2cd-soc-pinctrl",
	"marvell,berlin2cd-system-pinctrl",
	"marvell,berlin2q-soc-pinctrl",
	"marvell,berlin2q-system-pinctrl",
	"marvell,berlin4ct-avio-pinctrl",
	"marvell,berlin4ct-soc-pinctrl",
	"marvell,berlin4ct-system-pinctrl"

Required subnode-properties:
- groups: a list of strings describing the group names.
- function: a string describing the function used to mux the groups.

Example:

sys_pinctrl: pin-controller {
	compatible = "marvell,berlin2q-system-pinctrl";

	uart0_pmux: uart0-pmux {
		groups = "GSM12";
		function = "uart0";
	};
};

&uart0 {
	pinctrl-0 = <&uart0_pmux>;
	pinctrl-names = "default";
};