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/cdns,rtc.txt

@@ -0,0 +1,25 @@
+Cadence Real Time Clock
+
+The Cadence RTC controller with date, time and alarm capabilities.
+The alarm may wake the system from low-power state.
+
+Required properties:
+- compatible: Should be "cdns,rtc-r109v3"
+- reg: Specifies base physical address and size of the register area.
+- interrupts: A single interrupt specifier.
+- clocks: Must contain two entries:
+	- pclk: APB registers clock
+	- ref_clk: reference 1Hz or 100Hz clock, depending on IP configuration
+	See ../clocks/clock-bindings.txt for details.
+
+Example:
+        rtc0: rtc@fd080000 {
+        	compatible = "cdns,rtc-r109v3";
+        	reg = <0xfd080000 0x1000>;
+
+        	clock-names = "pclk", "ref_clk";
+        	clocks = <&sysclock>, <&refclock>;
+
+        	interrupt-parent = <&gic>;
+        	interrupts = <0 6 IRQ_TYPE_LEVEL_HIGH>;
+        };