ARM: dts: stm32: enable m4 coprocessor support on STM32MP157c-ed1

Enable m4 coprocessor for STM32MP157c-ed1 board.
Signed-off-by: Fabien Dessenne <fabien.dessenne@st.com>
Signed-off-by: Alexandre Torgue <alexandre.torgue@st.com>

arch/arm/boot/dts/stm32mp157c-ed1.dts

@@ -269,6 +269,16 @@ &iwdg2 {
 	status = "okay";
 };
 
+&m4_rproc {
+	memory-region = <&retram>, <&mcuram>, <&mcuram2>, <&vdev0vring0>,
+			<&vdev0vring1>, <&vdev0buffer>;
+	mboxes = <&ipcc 0>, <&ipcc 1>, <&ipcc 2>;
+	mbox-names = "vq0", "vq1", "shutdown";
+	interrupt-parent = <&exti>;
+	interrupts = <68 1>;
+	status = "okay";
+};
+
 &rng1 {
 	status = "okay";
 };