ARM: dts: stm32: add mcp23017 IO expander on I2C1 on stm32mp135f-dk

MCP23017 is an IO expander offering 16 input/output port expander with
interrupt output.
On stm32mp135f-dk, only INTA is routed (on PG12), but MCP23017 can mirror
the bank B interrupts on INTA, that's why the property microchip,irq-mirror
is used.

Signed-off-by: Amelie Delaunay <[e-mail]>
Signed-off-by: Alexandre Torgue <[e-mail]>

arch/arm/boot/dts/stm32mp135f-dk.dts

···
 	/delete-property/dmas;
 	/delete-property/dma-names;
 
+	mcp23017: pinctrl@21 {
+		compatible = "microchip,mcp23017";
+		reg = <0x21>;
+		gpio-controller;
+		#gpio-cells = <2>;
+		interrupts = <12 IRQ_TYPE_LEVEL_LOW>;
+		interrupt-parent = <&gpiog>;
+		pinctrl-names = "default";
+		pinctrl-0 = <&mcp23017_pins_a>;
+		interrupt-controller;
+		#interrupt-cells = <2>;
+		microchip,irq-mirror;
+	};
+
 	typec@53 {
 		compatible = "st,stm32g0-typec";
 		reg = <0x53>;