ARM: dts: cleanup exynos5440.dtsi

remove duplicated compatible

Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>

arch/arm/boot/dts/exynos5440.dtsi

@@ -58,11 +58,6 @@
 		};
 	};
 
-	common {
-		compatible = "samsung,exynos5440";
-
-	};
-
 	serial@B0000 {
 		compatible = "samsung,exynos4210-uart";
 		reg = <0xB0000 0x1000>;