ARM: dts: stm32: enable RTC support on stm32mp135f-dk

Enables the support of RTC on stm32mp135f-dk board.
Signed-off-by: Gabriel Fernandez <gabriel.fernandez@foss.st.com>
Signed-off-by: Valentin Caron <valentin.caron@foss.st.com>
Signed-off-by: Alexandre Torgue <alexandre.torgue@foss.st.com>

arch/arm/boot/dts/stm32mp135f-dk.dts

@@ -37,6 +37,10 @@ &iwdg2 {
 	status = "okay";
 };
 
+&rtc {
+	status = "okay";
+};
+
 &sdmmc1 {
 	pinctrl-names = "default", "opendrain", "sleep";
 	pinctrl-0 = <&sdmmc1_b4_pins_a &sdmmc1_clk_pins_a>;