dt-bindings: rtc: digicolor-rtc: move to trivial-rtc

Convert existing binding to dtschema to support validation.

This device meets the requirements to be moved to trivial-rtc
(compatible, reg and a single interrupt).
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20240326-rtc-yaml-v3-3-caa430ecace7@gmail.comSigned-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

Documentation/devicetree/bindings/rtc/digicolor-rtc.txt

-Conexant Digicolor Real Time Clock controller
-
-This binding currently supports the CX92755 SoC.
-
-Required properties:
-- compatible: should be "cnxt,cx92755-rtc"
-- reg: physical base address of the controller and length of memory mapped
-  region.
-- interrupts: rtc alarm interrupt
-
-Example:
-
-	rtc@f0000c30 {
-		compatible = "cnxt,cx92755-rtc";
-		reg = <0xf0000c30 0x18>;
-		interrupts = <25>;
-	};

Documentation/devicetree/bindings/rtc/trivial-rtc.yaml

@@ -24,6 +24,8 @@ properties:
       - abracon,abb5zes3
       # AB-RTCMC-32.768kHz-EOZ9: Real Time Clock/Calendar Module with I2C Interface
       - abracon,abeoz9
+      # Conexant Digicolor Real Time Clock Controller
+      - cnxt,cx92755-rtc
       # I2C, 32-Bit Binary Counter Watchdog RTC with Trickle Charger and Reset Input/Output
       - dallas,ds1374
       # Dallas DS1672 Real-time Clock