ARM: dts: stm32: add joystick support on stm32746g-eval

The joystick (B3) on stm32746g-eval uses gpios on STMFX gpio expander.
These gpios need a pin configuration (push-pull and bias-pull-up),
described under stmfx_pinctrl node.
Signed-off-by: Amelie Delaunay <amelie.delaunay@st.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Alexandre Torgue <alexandre.torgue@st.com>

arch/arm/boot/dts/stm32746g-eval.dts

@@ -87,6 +87,43 @@ button@0 {
 		};
 	};
 
+	joystick {
+		compatible = "gpio-keys";
+		#size-cells = <0>;
+		pinctrl-0 = <&joystick_pins>;
+		pinctrl-names = "default";
+		button-0 {
+			label = "JoySel";
+			linux,code = <KEY_ENTER>;
+			interrupt-parent = <&stmfx_pinctrl>;
+			interrupts = <0 IRQ_TYPE_EDGE_FALLING>;
+		};
+		button-1 {
+			label = "JoyDown";
+			linux,code = <KEY_DOWN>;
+			interrupt-parent = <&stmfx_pinctrl>;
+			interrupts = <1 IRQ_TYPE_EDGE_FALLING>;
+		};
+		button-2 {
+			label = "JoyLeft";
+			linux,code = <KEY_LEFT>;
+			interrupt-parent = <&stmfx_pinctrl>;
+			interrupts = <2 IRQ_TYPE_EDGE_FALLING>;
+		};
+		button-3 {
+			label = "JoyRight";
+			linux,code = <KEY_RIGHT>;
+			interrupt-parent = <&stmfx_pinctrl>;
+			interrupts = <3 IRQ_TYPE_EDGE_FALLING>;
+		};
+		button-4 {
+			label = "JoyUp";
+			linux,code = <KEY_UP>;
+			interrupt-parent = <&stmfx_pinctrl>;
+			interrupts = <4 IRQ_TYPE_EDGE_FALLING>;
+		};
+	};
+
 	usbotg_hs_phy: usb-phy {
 		#phy-cells = <0>;
 		compatible = "usb-nop-xceiv";
@@ -130,6 +167,12 @@ stmfx_pinctrl: stmfx-pin-controller {
 			interrupt-controller;
 			#interrupt-cells = <2>;
 			gpio-ranges = <&stmfx_pinctrl 0 0 24>;
+
+			joystick_pins: joystick {
+				pins = "gpio0", "gpio1", "gpio2", "gpio3", "gpio4";
+				drive-push-pull;
+				bias-pull-up;
+			};
 		};
 	};
 };