Documentation/bindings: Document the SafeXel cryptographic engine driver

The Inside Secure Safexcel cryptographic engine is found on some Marvell
SoCs (7k/8k). Document the bindings used by its driver.
Signed-off-by: NAntoine Tenart <antoine.tenart@free-electrons.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

Documentation/devicetree/bindings/crypto/inside-secure-safexcel.txt

+Inside Secure SafeXcel cryptographic engine
+
+Required properties:
+- compatible: Should be "inside-secure,safexcel-eip197".
+- reg: Base physical address of the engine and length of memory mapped region.
+- interrupts: Interrupt numbers for the rings and engine.
+- interrupt-names: Should be "ring0", "ring1", "ring2", "ring3", "eip", "mem".
+
+Optional properties:
+- clocks: Reference to the crypto engine clock.
+- dma-mask: The address mask limitation. Defaults to 64.
+
+Example:
+
+	crypto: crypto@800000 {
+		compatible = "inside-secure,safexcel-eip197";
+		reg = <0x800000 0x200000>;
+		interrupts = <GIC_SPI 34 IRQ_TYPE_LEVEL_HIGH>,
+			     <GIC_SPI 54 IRQ_TYPE_LEVEL_HIGH>,
+			     <GIC_SPI 55 IRQ_TYPE_LEVEL_HIGH>,
+			     <GIC_SPI 56 IRQ_TYPE_LEVEL_HIGH>,
+			     <GIC_SPI 57 IRQ_TYPE_LEVEL_HIGH>,
+			     <GIC_SPI 58 IRQ_TYPE_LEVEL_HIGH>;
+		interrupt-names = "mem", "ring0", "ring1", "ring2", "ring3",
+				  "eip";
+		clocks = <&cpm_syscon0 1 26>;
+		dma-mask = <0xff 0xffffffff>;
+		status = "disabled";
+	};