mmc: OCTEON: Add DT bindings for OCTEON MMC controller.

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+* OCTEON SD/MMC Host Controller
+
+This controller is present on some members of the Cavium OCTEON SoC
+family, provide an interface for eMMC, MMC and SD devices.  There is a
+single controller that may have several "slots" connected.  These
+slots appear as children of the main controller node.
+The DMA engine is an integral part of the controller block.
+
+Required properties:
+- compatible : Should be "cavium,octeon-6130-mmc" or "cavium,octeon-7890-mmc"
+- reg : Two entries:
+	1) The base address of the MMC controller register bank
+	2) The base address of the MMC DMA engine register bank
+- interrupts :
+	For "cavium,octeon-6130-mmc": two entries:
+	1) The MMC controller interrupt line
+	2) The MMC DMA engine interrupt line
+	For "cavium,octeon-7890-mmc": nine entries:
+	1) Next block transfer of a multiblock transfer has completed (BUF_DONE)
+	2) Operation completed successfully (CMD_DONE)
+	3) DMA transfer completed successfully (DMA_DONE)
+	4) Operation encountered an error (CMD_ERR)
+	5) DMA transfer encountered an error (DMA_ERR)
+	6) Switch operation completed successfully (SWITCH_DONE)
+	7) Switch operation encountered an error (SWITCH_ERR)
+	8) Internal DMA engine request completion interrupt (DONE)
+	9) Internal DMA FIFO underflow (FIFO)
+- #address-cells : Must be <1>
+- #size-cells : Must be <0>
+
+Required properties of child nodes:
+- compatible : Should be
+  - "cavium,octeon-6130-mmc-slot"
+- reg : The slot number.
+
+Optional properties of child nodes:
+- cd-gpios : Specify GPIOs for card detection
+- wp-gpios : Specify GPIOs for write protection
+- bus-width : for data lines present in the slot. Default is 8.
+- max-frequency : Maximum operating frequency of the slot. Default is 52000000.
+- spi-max-frequency (DEPRECATED)
+
+Cavium specific properties of child nodes:
+- power-gpios : Specify GPIOs for power control
+- cavium,cmd-clk-skew : the amount of delay (in pS) past the clock edge
+	to sample the command pin.
+- cavium,dat-clk-skew : the amount of delay (in pS) past the clock edge
+	to sample the data pin.
+- cavium,bus-max-width (DEPRECATED)
+
+Example:
+	mmc@1180000002000 {
+		compatible = "cavium,octeon-6130-mmc";
+		reg = <0x11800 0x00002000 0x0 0x100>,
+		      <0x11800 0x00000168 0x0 0x20>;
+		#address-cells = <1>;
+		#size-cells = <0>;
+		/* EMM irq, DMA irq */
+		interrupts = <1 19>, <0 63>;
+
+		/* The board only has a single MMC slot */
+		mmc-slot@0 {
+			compatible = "cavium,octeon-6130-mmc-slot";
+			reg = <0>;
+			max-frequency = <20000000>;
+			/* bus width can be 1, 4 or 8 */
+			bus-width = <8>;
+			cd-gpios = <&gpio 9 0>;
+			wp-gpios = <&gpio 10 0>;
+			power-gpios = <&gpio 8 0>;
+		};
+	};