ARM: dts: stm32: Clean led-red node for stm32mp135f-dk-u-boot

Remove "color" property from led-red node which is not supported
by U-Boot.

Signed-off-by: Patrice Chotard <patrice.chotard@foss.st.com>
Reviewed-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
diff --git a/arch/arm/dts/stm32mp135f-dk-u-boot.dtsi b/arch/arm/dts/stm32mp135f-dk-u-boot.dtsi
index 8f42735..f004e98 100644
--- a/arch/arm/dts/stm32mp135f-dk-u-boot.dtsi
+++ b/arch/arm/dts/stm32mp135f-dk-u-boot.dtsi
@@ -35,7 +35,6 @@
 		};
 
 		led-red {
-			color = <LED_COLOR_ID_RED>;
 			gpios = <&gpioa 13 GPIO_ACTIVE_LOW>;
 		};
 	};