ARM: dts: stm32: add RTC support to stm32mp157c

Add support for RTC (Real Time Clock) to STM32MP157C SoC.
Signed-off-by: Amelie Delaunay <amelie.delaunay@st.com>
Signed-off-by: Alexandre Torgue <alexandre.torgue@st.com>

arch/arm/boot/dts/stm32mp157c.dtsi

@@ -863,6 +863,15 @@ i2c4: i2c@5c002000 {
 			status = "disabled";
 		};
 
+		rtc: rtc@5c004000 {
+			compatible = "st,stm32mp1-rtc";
+			reg = <0x5c004000 0x400>;
+			clocks = <&rcc RTCAPB>, <&rcc RTC>;
+			clock-names = "pclk", "rtc_ck";
+			interrupts = <GIC_SPI 3 IRQ_TYPE_LEVEL_HIGH>;
+			status = "disabled";
+		};
+
 		i2c6: i2c@5c009000 {
 			compatible = "st,stm32f7-i2c";
 			reg = <0x5c009000 0x400>;