dt-bindings: rtc: Add Realtek RTD1295

Add a binding for the RTC on the Realtek RTD119x/RTD129x SoC families.
Acked-by: NRob Herring <robh@kernel.org>
Signed-off-by: NAndreas Färber <afaerber@suse.de>
Signed-off-by: NAlexandre Belloni <alexandre.belloni@free-electrons.com>

Documentation/devicetree/bindings/rtc/realtek,rtd119x.txt

+Realtek RTD129x Real-Time Clock
+===============================
+
+Required properties:
+- compatible :  Should be "realtek,rtd1295-rtc"
+- reg        :  Specifies the physical base address and size
+- clocks     :  Specifies the clock gate
+
+
+Example:
+
+	rtc@9801b600 {
+		compatible = "realtek,rtd1295-clk";
+		reg = <0x9801b600 0x100>;
+		clocks = <&clkc RTD1295_CLK_EN_MISC_RTC>;
+	};