ARM: dts: stm32: enable RTC on stm32f769-disco

This patch enables RTC on stm32f769-disco.
Signed-off-by: Amelie Delaunay <amelie.delaunay@st.com>
Signed-off-by: Alexandre Torgue <alexandre.torgue@st.com>

arch/arm/boot/dts/stm32f769-disco.dts

@@ -104,6 +104,10 @@ &clk_hse {
 	clock-frequency = <25000000>;
 };
 
+&rtc {
+	status = "okay";
+};
+
 &usart1 {
 	pinctrl-0 = <&usart1_pins_a>;
 	pinctrl-names = "default";