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/mfd/ti-keystone-devctrl.txt

@@ -0,0 +1,19 @@
+* Device tree bindings for Texas Instruments keystone device state control
+
+The Keystone II devices have a set of registers that are used to control
+the status of its peripherals. This node is intended to allow access to
+this functionality.
+
+Required properties:
+
+- compatible:		"ti,keystone-devctrl", "syscon"
+
+- reg:			contains offset/length value for device state control
+			registers space.
+
+Example:
+
+devctrl: device-state-control@02620000 {
+	compatible = "ti,keystone-devctrl", "syscon";
+	reg = <0x02620000 0x1000>;
+};