* Core Clock bindings for Marvell MVEBU SoCs

Marvell MVEBU SoCs usually allow to determine core clock frequencies by
reading the Sample-At-Reset (SAR) register. The core clock consumer should
specify the desired clock by having the clock ID in its "clocks" phandle cell.

The following is a list of provided IDs and clock names on Armada 370/XP:
 0 = tclk    (Internal Bus clock)
 1 = cpuclk  (CPU clock)
 2 = nbclk   (L2 Cache clock)
 3 = hclk    (DRAM control clock)
 4 = dramclk (DDR clock)

The following is a list of provided IDs and clock names on Armada 375:
 0 = tclk    (Internal Bus clock)
 1 = cpuclk  (CPU clock)
 2 = l2clk   (L2 Cache clock)
 3 = ddrclk  (DDR clock)

The following is a list of provided IDs and clock names on Armada 380/385:
 0 = tclk    (Internal Bus clock)
 1 = cpuclk  (CPU clock)
 2 = l2clk   (L2 Cache clock)
 3 = ddrclk  (DDR clock)

The following is a list of provided IDs and clock names on Kirkwood and Dove:
 0 = tclk   (Internal Bus clock)
 1 = cpuclk (CPU0 clock)
 2 = l2clk  (L2 Cache clock derived from CPU0 clock)
 3 = ddrclk (DDR controller clock derived from CPU0 clock)

Required properties:
- compatible : shall be one of the following:
	"marvell,armada-370-core-clock" - For Armada 370 SoC core clocks
	"marvell,armada-375-core-clock" - For Armada 375 SoC core clocks
	"marvell,armada-380-core-clock" - For Armada 380/385 SoC core clocks
	"marvell,armada-xp-core-clock" - For Armada XP SoC core clocks
	"marvell,dove-core-clock" - for Dove SoC core clocks
	"marvell,kirkwood-core-clock" - for Kirkwood SoC (except mv88f6180)
	"marvell,mv88f6180-core-clock" - for Kirkwood MV88f6180 SoC
- reg : shall be the register address of the Sample-At-Reset (SAR) register
- #clock-cells : from common clock binding; shall be set to 1

Optional properties:
- clock-output-names : from common clock binding; allows overwrite default clock
	output names ("tclk", "cpuclk", "l2clk", "ddrclk")

Example:

core_clk: core-clocks@d0214 {
	compatible = "marvell,dove-core-clock";
	reg = <0xd0214 0x4>;
	#clock-cells = <1>;
};

spi0: spi@10600 {
	compatible = "marvell,orion-spi";
	/* ... */
	/* get tclk from core clock provider */
	clocks = <&core_clk 0>;
};