ARM: dts: change to correct compatible string for exynos5420 hdmi

Replace compatible string for HDMI node in Exynos5420. Since
latest restructring in Drm hdmi driver, it is agreed to use
a seperate compatible string for Exynos5420 HDMI IP siince it
uses APB mapped Phy.
Signed-off-by: Rahul Sharma <rahul.sharma@samsung.com>
Acked-by: Tomasz Figa <t.figa@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>

arch/arm/boot/dts/exynos5420.dtsi

@@ -651,7 +651,7 @@ hsi2c_10: i2c@12E20000 {
 	};
 
 	hdmi: hdmi@14530000 {
-		compatible = "samsung,exynos4212-hdmi";
+		compatible = "samsung,exynos5420-hdmi";
 		reg = <0x14530000 0x70000>;
 		interrupts = <0 95 0>;
 		clocks = <&clock CLK_HDMI>, <&clock CLK_SCLK_HDMI>,