ARM: dts: stm32: Add ipcc mailbox support on stm32mp1

Add IPCC mailbox support on stm32mp157 eval and disco boards.

Signed-off-by: Fabien Dessenne <fabien.dessenne@st.com>
Reviewed-by: Patrice Chotard <patrice.chotard@st.com>
diff --git a/arch/arm/dts/stm32mp157a-dk1.dts b/arch/arm/dts/stm32mp157a-dk1.dts
index e36773d..b8dd4ba 100644
--- a/arch/arm/dts/stm32mp157a-dk1.dts
+++ b/arch/arm/dts/stm32mp157a-dk1.dts
@@ -228,6 +228,10 @@
 	};
 };
 
+&ipcc {
+	status = "okay";
+};
+
 &iwdg2 {
 	timeout-sec = <32>;
 	status = "okay";