ARM: dts: stm32: Rework DDR DT inclusion

Adjust the DDR configuration dtsi such that they only generate the
DRAM configuration node, the DDR controller node is moved into the
stm32mp157-u-boot.dtsi itself. This permits including multiple DDR
configuration dtsi files in board DT.

Reviewed-by: Patrick Delaunay <patrick.delaunay@st.com>
Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Cc: Patrick Delaunay <patrick.delaunay@st.com>
Cc: Patrice Chotard <patrice.chotard@st.com>
diff --git a/arch/arm/dts/stm32mp15-u-boot.dtsi b/arch/arm/dts/stm32mp15-u-boot.dtsi
index 8f9535a..1279589 100644
--- a/arch/arm/dts/stm32mp15-u-boot.dtsi
+++ b/arch/arm/dts/stm32mp15-u-boot.dtsi
@@ -36,6 +36,31 @@
 
 	soc {
 		u-boot,dm-pre-reloc;
+
+		ddr: ddr@5a003000 {
+			u-boot,dm-pre-reloc;
+
+			compatible = "st,stm32mp1-ddr";
+
+			reg = <0x5A003000 0x550
+			       0x5A004000 0x234>;
+
+			clocks = <&rcc AXIDCG>,
+				 <&rcc DDRC1>,
+				 <&rcc DDRC2>,
+				 <&rcc DDRPHYC>,
+				 <&rcc DDRCAPB>,
+				 <&rcc DDRPHYCAPB>;
+
+			clock-names = "axidcg",
+				      "ddrc1",
+				      "ddrc2",
+				      "ddrphyc",
+				      "ddrcapb",
+				      "ddrphycapb";
+
+			status = "okay";
+		};
 	};
 };