dt-bindings: rtc: Add Realtek RTD1295

Realtek RTD129x Real-Time Clock

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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>;

	};