ARM: dts: Keep LDO4 always ON for exynos5250-arndale board

LDO4 regulator was getting disabled preventing the system from
going into low power states. Keep it always on to fix it.
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>

arch/arm/boot/dts/exynos5250-arndale.dts

@@ -107,6 +107,7 @@ ldo4_reg: LDO4 {
 					regulator-name = "VDD_IOPERI_1.8V";
 					regulator-min-microvolt = <1800000>;
 					regulator-max-microvolt = <1800000>;
+					regulator-always-on;
 					op_mode = <1>;
 				};