ARM: dts: stm32: enable IPCC mailbox support on STM32MP157c-ed1

Enable STM32 IPCC mailbox driver 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

@@ -84,6 +84,10 @@ &i2c4 {
 	status = "okay";
 };
 
+&ipcc {
+	status = "okay";
+};
+
 &iwdg2 {
 	timeout-sec = <32>;
 	status = "okay";