arm64: dts: imx8mn-ddr4-evk: correct ldo1/ldo2 voltage range

Correct ldo1 voltage range from wrong high group(3.0V~3.3V) to low group
(1.6V~1.9V) because the ldo1 should be 1.8V. Actually, two voltage groups
have been supported at bd718x7-regulator driver, hence, just corrrect the
voltage range to 1.6V~3.3V. For ldo2@0.8V, correct voltage range too.
Otherwise, ldo1 would be kept @3.0V and ldo2@0.9V which violate i.mx8mn
datasheet as the below warning log in kernel:

[    0.995524] LDO1: Bringing 1800000uV into 3000000-3000000uV
[    0.999196] LDO2: Bringing 800000uV into 900000-900000uV

Fixes: 3e44dd09 ("arm64: dts: imx8mn-ddr4-evk: Add rohm,bd71847 PMIC support")
Cc: stable@vger.kernel.org
Signed-off-by: Robin Gong <yibin.gong@nxp.com>
Reviewed-by: Dong Aisheng <aisheng.dong@nxp.com>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm64/boot/dts/freescale/imx8mn-ddr4-evk.dts

@@ -113,7 +113,7 @@ buck6_reg: BUCK6 {
 
 			ldo1_reg: LDO1 {
 				regulator-name = "LDO1";
-				regulator-min-microvolt = <3000000>;
+				regulator-min-microvolt = <1600000>;
 				regulator-max-microvolt = <3300000>;
 				regulator-boot-on;
 				regulator-always-on;
@@ -121,7 +121,7 @@ ldo1_reg: LDO1 {
 
 			ldo2_reg: LDO2 {
 				regulator-name = "LDO2";
-				regulator-min-microvolt = <900000>;
+				regulator-min-microvolt = <800000>;
 				regulator-max-microvolt = <900000>;
 				regulator-boot-on;
 				regulator-always-on;