ARM: dts: stm32: add orange and blue leds on stm32746g-eval

Orange (LD2) and blue (LD4) leds on stm32746g-eval are connected on
STMFX gpio expander, offset 17 and 19.
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

@@ -70,9 +70,15 @@ green {
 			gpios = <&gpiof 10 1>;
 			linux,default-trigger = "heartbeat";
 		};
+		orange {
+			gpios = <&stmfx_pinctrl 17 1>;
+		};
 		red {
 			gpios = <&gpiob 7 1>;
 		};
+		blue {
+			gpios = <&stmfx_pinctrl 19 1>;
+		};
 	};
 
 	gpio_keys {