ARM: dts: exynos: Fix min/max buck4 for GPU on Arndale board

Required to have GPU voltage scaling working properly.
Signed-off-by: Guillaume Gardet <guillaume.gardet@arm.com>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>

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

@@ -461,8 +461,8 @@ buck3_reg: BUCK3 {
 
 			buck4_reg: BUCK4 {
 				regulator-name = "vdd_g3d";
-				regulator-min-microvolt = <1000000>;
-				regulator-max-microvolt = <1000000>;
+				regulator-min-microvolt = <850000>;
+				regulator-max-microvolt = <1300000>;
 				regulator-always-on;
 				regulator-boot-on;
 				op_mode = <1>;