dt-bindings: ata: drop unused Exynos SATA bindings

* Samsung AHCI SATA Controller

SATA nodes are defined to describe on-chip Serial ATA controllers.

Each SATA controller should have its own node.

Required properties:

- compatible		: compatible list, contains "samsung,exynos5-sata"

- interrupts		: <interrupt mapping for SATA IRQ>

- reg			: <registers mapping>

- samsung,sata-freq	: <frequency in MHz>

- phys			: Must contain exactly one entry as specified

			  in phy-bindings.txt

- phy-names		: Must be "sata-phy"

Optional properties:

- clocks		: Must contain an entry for each entry in clock-names.

- clock-names		: Shall be "sata" for the external SATA bus clock,

			  and "sclk_sata" for the internal controller clock.

Example:

	sata@122f0000 {

		compatible = "snps,dwc-ahci";

		samsung,sata-freq = <66>;

		reg = <0x122f0000 0x1ff>;

		interrupts = <0 115 0>;

		clocks = <&clock 277>, <&clock 143>;

		clock-names = "sata", "sclk_sata";

		phys = <&sata_phy>;

		phy-names = "sata-phy";

	};