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/rtc/orion-rtc.txt

@@ -0,0 +1,18 @@
+* Mvebu Real Time Clock
+
+RTC controller for the Kirkwood, the Dove, the Armada 370 and the
+Armada XP SoCs
+
+Required properties:
+- compatible : Should be "marvell,orion-rtc"
+- reg: physical base address of the controller and length of memory mapped
+  region.
+- interrupts: IRQ line for the RTC.
+
+Example:
+
+rtc@10300 {
+        compatible = "marvell,orion-rtc";
+        reg = <0xd0010300 0x20>;
+        interrupts = <50>;
+};