ARM: dts: exynos: Adjust buck[78] regulators to supported values on Arndale Octa

The datasheet of S2MPS11 PMIC is slightly non-consistent in buck[78]
voltage regulators values.

1. The voltage tables for configuring their registers mention range of
   voltages: 0.750 V to 3.55 V,
2. The constrains in electrical specifications say output voltage range
   to be different (buck7: 1.2 V to 1.5 V, buck8: 1.8 V to 2.1 V).

Adjust the ranges to match the electrical specifications to stay on the
safe side.  Anyway these regulators stay at default value so this should
not have effect.
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>

arch/arm/boot/dts/exynos5420-arndale-octa.dts

@@ -723,15 +723,15 @@ regulator-state-mem {
 
 			buck7_reg: BUCK7 {
 				regulator-name = "VIN_LLDO_1V4";
-				regulator-min-microvolt = <800000>;
+				regulator-min-microvolt = <1200000>;
 				regulator-max-microvolt = <1500000>;
 				regulator-always-on;
 			};
 
 			buck8_reg: BUCK8 {
 				regulator-name = "VIN_MLDO_2V0";
-				regulator-min-microvolt = <800000>;
-				regulator-max-microvolt = <2000000>;
+				regulator-min-microvolt = <1800000>;
+				regulator-max-microvolt = <2100000>;
 				regulator-always-on;
 			};