dt-bindings: Add devicetree bindings

Add snapshot of device tree bindings from keystone common kernel, branch
"android-mainline-keystone-qcom-release" at c4c12103f9c0 ("Snap for 9228065
from e32903b9a63bb558df8b803b076619c53c16baad to
android-mainline-keystone-qcom-release").

Change-Id: I7682079615cbd9f29340a5c1f2a1d84ec441a1f1
Signed-off-by: Melody Olvera <quic_molvera@quicinc.com>

bindings/xillybus/xillybus.txt

@@ -0,0 +1,18 @@
+* Xillybus driver for generic FPGA interface
+
+Required properties:
+- compatible: Should be "xillybus,xillybus-1.00.a"
+- reg: Address and length of the register set for the device
+- interrupts: Contains one interrupt node, typically consisting of three cells.
+
+Optional properties:
+- dma-coherent: Present if DMA operations are coherent
+
+Example:
+
+	xillybus@ff200400 {
+		compatible = "xillybus,xillybus-1.00.a";
+		reg = < 0xff200400 0x00000080 >;
+		interrupts = < 0 40 1 >;
+		interrupt-parent = <&intc>;
+	} ;