ARM: dts: stm32: Add exti support for stm32mp157c

This patch adds external interrupt (exti) support
on stm32mp157c SoC.

Signed-off-by: Ludovic Barre <ludovic.barre@st.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

arch/arm/boot/dts/stm32mp157c.dtsi

@@ -183,6 +183,13 @@
 			status = "disabled";
 		};
 
+		exti: interrupt-controller@5000d000 {
+			compatible = "st,stm32mp1-exti", "syscon";
+			interrupt-controller;
+			#interrupt-cells = <2>;
+			reg = <0x5000d000 0x400>;
+		};
+
 		usart1: serial@5c000000 {
 			compatible = "st,stm32h7-uart";
 			reg = <0x5c000000 0x400>;