arm64: dts: imx8mq-librem5: Align regulator names with schema

Device tree schema expects regulator names to be lowercase.  This fixes
dtbs_check warnings like:

  pmic@4b: regulators:LDO1:regulator-name:0: 'LDO1' does not match '^ldo[1-7]$'
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm64/boot/dts/freescale/imx8mq-librem5.dtsi

@@ -645,7 +645,7 @@ pmic: pmic@4b {
 
 		regulators {
 			buck1_reg: BUCK1 {
-				regulator-name = "BUCK1";
+				regulator-name = "buck1";
 				regulator-min-microvolt = <700000>;
 				regulator-max-microvolt = <1300000>;
 				regulator-ramp-delay = <1250>;
@@ -656,7 +656,7 @@ buck1_reg: BUCK1 {
 			};
 
 			buck2_reg: BUCK2 {
-				regulator-name = "BUCK2";
+				regulator-name = "buck2";
 				regulator-min-microvolt = <700000>;
 				regulator-max-microvolt = <1300000>;
 				regulator-ramp-delay = <1250>;
@@ -666,7 +666,7 @@ buck2_reg: BUCK2 {
 			};
 
 			buck3_reg: BUCK3 {
-				regulator-name = "BUCK3";
+				regulator-name = "buck3";
 				regulator-min-microvolt = <700000>;
 				regulator-max-microvolt = <1300000>;
 				rohm,dvs-run-voltage = <900000>;
@@ -674,42 +674,42 @@ buck3_reg: BUCK3 {
 			};
 
 			buck4_reg: BUCK4 {
-				regulator-name = "BUCK4";
+				regulator-name = "buck4";
 				regulator-min-microvolt = <700000>;
 				regulator-max-microvolt = <1300000>;
 				rohm,dvs-run-voltage = <1000000>;
 			};
 
 			buck5_reg: BUCK5 {
-				regulator-name = "BUCK5";
+				regulator-name = "buck5";
 				regulator-min-microvolt = <700000>;
 				regulator-max-microvolt = <1350000>;
 				regulator-always-on;
 			};
 
 			buck6_reg: BUCK6 {
-				regulator-name = "BUCK6";
+				regulator-name = "buck6";
 				regulator-min-microvolt = <3000000>;
 				regulator-max-microvolt = <3300000>;
 				regulator-always-on;
 			};
 
 			buck7_reg: BUCK7 {
-				regulator-name = "BUCK7";
+				regulator-name = "buck7";
 				regulator-min-microvolt = <1605000>;
 				regulator-max-microvolt = <1995000>;
 				regulator-always-on;
 			};
 
 			buck8_reg: BUCK8 {
-				regulator-name = "BUCK8";
+				regulator-name = "buck8";
 				regulator-min-microvolt = <800000>;
 				regulator-max-microvolt = <1400000>;
 				regulator-always-on;
 			};
 
 			ldo1_reg: LDO1 {
-				regulator-name = "LDO1";
+				regulator-name = "ldo1";
 				regulator-min-microvolt = <3000000>;
 				regulator-max-microvolt = <3300000>;
 				/* leave on for snvs power button */
@@ -717,7 +717,7 @@ ldo1_reg: LDO1 {
 			};
 
 			ldo2_reg: LDO2 {
-				regulator-name = "LDO2";
+				regulator-name = "ldo2";
 				regulator-min-microvolt = <900000>;
 				regulator-max-microvolt = <900000>;
 				/* leave on for snvs power button */
@@ -725,14 +725,14 @@ ldo2_reg: LDO2 {
 			};
 
 			ldo3_reg: LDO3 {
-				regulator-name = "LDO3";
+				regulator-name = "ldo3";
 				regulator-min-microvolt = <1800000>;
 				regulator-max-microvolt = <3300000>;
 				regulator-always-on;
 			};
 
 			ldo4_reg: LDO4 {
-				regulator-name = "LDO4";
+				regulator-name = "ldo4";
 				regulator-min-microvolt = <900000>;
 				regulator-max-microvolt = <1800000>;
 				regulator-always-on;
@@ -740,7 +740,7 @@ ldo4_reg: LDO4 {
 
 			ldo5_reg: LDO5 {
 				/* VDD_PHY_0V9 - MIPI and HDMI domains */
-				regulator-name = "LDO5";
+				regulator-name = "ldo5";
 				regulator-min-microvolt = <1800000>;
 				regulator-max-microvolt = <3300000>;
 				regulator-always-on;
@@ -748,7 +748,7 @@ ldo5_reg: LDO5 {
 
 			ldo6_reg: LDO6 {
 				/* VDD_PHY_0V9 - MIPI, HDMI and USB domains */
-				regulator-name = "LDO6";
+				regulator-name = "ldo6";
 				regulator-min-microvolt = <900000>;
 				regulator-max-microvolt = <1800000>;
 				regulator-always-on;
@@ -756,7 +756,7 @@ ldo6_reg: LDO6 {
 
 			ldo7_reg: LDO7 {
 				/* VDD_PHY_3V3 - USB domain */
-				regulator-name = "LDO7";
+				regulator-name = "ldo7";
 				regulator-min-microvolt = <1800000>;
 				regulator-max-microvolt = <3300000>;
 				regulator-always-on;