ARM: dts: stm32: Add exti support to stm32mp157 pinctrl

This patch adds support of external interrupt for
gpio[a..k], gpioz

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

arch/arm/boot/dts/stm32mp157-pinctrl.dtsi

@@ -12,6 +12,8 @@
 			#size-cells = <1>;
 			compatible = "st,stm32mp157-pinctrl";
 			ranges = <0 0x50002000 0xa400>;
+			interrupt-parent = <&exti>;
+			st,syscfg = <&exti 0x60 0xff>;
 			pins-are-numbered;
 
 			gpioa: gpio@50002000 {
@@ -166,6 +168,8 @@
 			compatible = "st,stm32mp157-z-pinctrl";
 			ranges = <0 0x54004000 0x400>;
 			pins-are-numbered;
+			interrupt-parent = <&exti>;
+			st,syscfg = <&exti 0x60 0xff>;
 			status = "disabled";
 
 			gpioz: gpio@54004000 {