ARM: dts: Add STMFX gpio expander support for stm32mp157c-ev1

Adds alias to set the pincontrol seq id.
For STMFX gpio expander, force sequence number after
the last bank (GPIOZ) to avoid conflict between STM32MP and STMFX
gpio bank sequence number.

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
Signed-off-by: Patrice Chotard <patrice.chotard@st.com>
diff --git a/arch/arm/dts/stm32mp157-u-boot.dtsi b/arch/arm/dts/stm32mp157-u-boot.dtsi
index 2594702..ab6f673 100644
--- a/arch/arm/dts/stm32mp157-u-boot.dtsi
+++ b/arch/arm/dts/stm32mp157-u-boot.dtsi
@@ -17,6 +17,8 @@
 		gpio9 = &gpioj;
 		gpio10 = &gpiok;
 		gpio25 = &gpioz;
+		pinctrl0 = &pinctrl;
+		pinctrl1 = &pinctrl_z;
 	};
 
 	config {
diff --git a/arch/arm/dts/stm32mp157c-ev1-u-boot.dtsi b/arch/arm/dts/stm32mp157c-ev1-u-boot.dtsi
index be3b152..6a18d03 100644
--- a/arch/arm/dts/stm32mp157c-ev1-u-boot.dtsi
+++ b/arch/arm/dts/stm32mp157c-ev1-u-boot.dtsi
@@ -7,8 +7,10 @@
 
 / {
 	aliases {
+		gpio26 = &stmfx_pinctrl;
 		i2c1 = &i2c2;
 		i2c4 = &i2c5;
+		pinctrl2 = &stmfx_pinctrl;
 		spi0 = &qspi;
 	};
 };
diff --git a/arch/arm/dts/stm32mp157c-ev1.dts b/arch/arm/dts/stm32mp157c-ev1.dts
index e114c9b..a6ee379 100644
--- a/arch/arm/dts/stm32mp157c-ev1.dts
+++ b/arch/arm/dts/stm32mp157c-ev1.dts
@@ -98,6 +98,24 @@
 	i2c-scl-rising-time-ns = <185>;
 	i2c-scl-falling-time-ns = <20>;
 	status = "okay";
+
+	stmfx: stmfx@42 {
+		compatible = "st,stmfx-0300";
+		reg = <0x42>;
+		interrupts = <8 IRQ_TYPE_EDGE_RISING>;
+		interrupt-parent = <&gpioi>;
+		vdd-supply = <&v3v3>;
+
+		stmfx_pinctrl: stmfx-pin-controller {
+			compatible = "st,stmfx-0300-pinctrl";
+			gpio-controller;
+			#gpio-cells = <2>;
+			interrupt-controller;
+			#interrupt-cells = <2>;
+			gpio-ranges = <&stmfx_pinctrl 0 0 24>;
+			status = "disabled";
+		};
+	};
 };
 
 &i2c5 {