ARM: DT: qcom: Add Qualcomm crypto driver binding document

Here is Qualcomm crypto driver device tree binding documentation
to used as a reference example.

Signed-off-by: Stanimir Varbanov <[e-mail]>
Signed-off-by: Herbert Xu <[e-mail]>

Documentation/devicetree/bindings/crypto/qcom-qce.txt

···
+Qualcomm crypto engine driver
+
+Required properties:
+
+- compatible  : should be "qcom,crypto-v5.1"
+- reg         : specifies base physical address and size of the registers map
+- clocks      : phandle to clock-controller plus clock-specifier pair
+- clock-names : "iface" clocks register interface
+                "bus" clocks data transfer interface
+                "core" clocks rest of the crypto block
+- dmas        : DMA specifiers for tx and rx dma channels. For more see
+                Documentation/devicetree/bindings/dma/dma.txt
+- dma-names   : DMA request names should be "rx" and "tx"
+
+Example:
+	crypto@fd45a000 {
+		compatible = "qcom,crypto-v5.1";
+		reg = <0xfd45a000 0x6000>;
+		clocks = <&gcc GCC_CE2_AHB_CLK>,
+			 <&gcc GCC_CE2_AXI_CLK>,
+			 <&gcc GCC_CE2_CLK>;
+		clock-names = "iface", "bus", "core";
+		dmas = <&cryptobam 2>, <&cryptobam 3>;
+		dma-names = "rx", "tx";
+	};