ARM: dts: exynos: Fix DTC unit name warnings in Exynos3250

Fix following DTC warnings in Exynos3250 boards:

Warning (unit_address_vs_reg): Node /soc/video-phy@10020710 has a unit name, but no reg property
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Reviewed-by: Javier Martinez Canillas <javier@osg.samsung.com>

arch/arm/boot/dts/exynos3250.dtsi

@@ -155,7 +155,7 @@ pmu_system_controller: system-controller@10020000 {
 			interrupt-parent = <&gic>;
 		};
 
-		mipi_phy: video-phy@10020710 {
+		mipi_phy: video-phy {
 			compatible = "samsung,s5pv210-mipi-video-phy";
 			#phy-cells = <1>;
 			syscon = <&pmu_system_controller>;