ARM: dts: stm32: update led nodes names for stm32f249-disco

Update led nodes names to be aligned with yaml description
Signed-off-by: Benjamin Gaignard <benjamin.gaignard@st.com>
Signed-off-by: Alexandre Torgue <alexandre.torgue@st.com>

arch/arm/boot/dts/stm32f429-disco.dts

@@ -72,10 +72,10 @@ aliases {
 
 	leds {
 		compatible = "gpio-leds";
-		red {
+		led-red {
 			gpios = <&gpiog 14 0>;
 		};
-		green {
+		led-green {
 			gpios = <&gpiog 13 0>;
 			linux,default-trigger = "heartbeat";
 		};