feat(stm32mp25-fdts): add DDR power supplies

Add the required power supplies for DDR nodes. The power supplies are
provided by STPMIC2 regulators.

Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
Change-Id: I951da75a554bc4fbfbc69ea9cd1171d99ed7ce46
diff --git a/fdts/stm32mp257f-ev1.dts b/fdts/stm32mp257f-ev1.dts
index d2b5e55..75de195 100644
--- a/fdts/stm32mp257f-ev1.dts
+++ b/fdts/stm32mp257f-ev1.dts
@@ -37,6 +37,13 @@
 	};
 };
 
+&ddr {
+	vdd-supply = <&vdd_ddr>;
+	vtt-supply = <&vtt_ddr>;
+	vpp-supply = <&vpp_ddr>;
+	vref-supply = <&vref_ddr>;
+};
+
 &i2c7 {
 	pinctrl-names = "default";
 	pinctrl-0 = <&i2c7_pins_a>;