devicetree:bindings: add devicetree bindings for ceva ahci

Binding for CEVA AHCI SATA Controller

Required properties:

  - reg: Physical base address and size of the controller's register area.

  - compatible: Compatibility string. Must be 'ceva,ahci-1v84'.

  - clocks: Input clock specifier. Refer to common clock bindings.

  - interrupts: Interrupt specifier. Refer to interrupt binding.

Optional properties:

  - ceva,broken-gen2: limit to gen1 speed instead of gen2.

Examples:

	ahci@fd0c0000 {

		compatible = "ceva,ahci-1v84";

		reg = <0xfd0c0000 0x200>;

		interrupt-parent = <&gic>;

		interrupts = <0 133 4>;

		clocks = <&clkc SATA_CLK_ID>;

		ceva,broken-gen2;

	};