ARM: dts: mstar: Add rtc device node

This adds the definition of the rtc device node. The RTC being able to
work with the oscillator at 12Mhz for now, it shares the same xtal than
the watchdog.
Signed-off-by: Romain Perier <romain.perier@gmail.com>
Signed-off-by: Daniel Palmer <daniel@0x0f.com>
Link: https://lore.kernel.org/all/20210823171613.18941-4-romain.perier@gmail.com

arch/arm/boot/dts/mstar-v7.dtsi

@@ -109,12 +109,20 @@ reboot {
 				mask = <0x79>;
 			};
 
+			rtc@2400 {
+				compatible = "mstar,msc313-rtc";
+				reg = <0x2400 0x40>;
+				clocks = <&xtal_div2>;
+				interrupts-extended = <&intc_irq GIC_SPI 44 IRQ_TYPE_LEVEL_HIGH>;
+			};
+
 			watchdog@6000 {
 				compatible = "mstar,msc313e-wdt";
 				reg = <0x6000 0x1f>;
 				clocks = <&xtal_div2>;
 			};
 
+
 			intc_fiq: interrupt-controller@201310 {
 				compatible = "mstar,mst-intc";
 				reg = <0x201310 0x40>;