arm64: dts: imx8mp-verdin: Label ldo5 and link to usdhc2

This commit labels LDO5 as `reg_vdd_sdio` in `imx8mp-verdin.dtsi` to
facilitate changing its voltage to 1.8V, necessary for an SDIO
peripheral that requires 1.8V at default and high-speed modes.

Additionally, it links `reg_vdd_sdio` to `&usdhc2`, aligning with the
hardware configuration specified in the datasheet.
Signed-off-by: Philippe Schenker <philippe.schenker@impulsing.ch>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm64/boot/dts/freescale/imx8mp-verdin.dtsi

@@ -552,7 +552,7 @@ LDO4 {
 				regulator-name = "On-module +V3.3_ADC (LDO4)";
 			};
 
-			LDO5 {
+			reg_vdd_sdio: LDO5 {
 				regulator-max-microvolt = <3300000>;
 				regulator-min-microvolt = <1800000>;
 				regulator-name = "On-module +V3.3_1.8_SD (LDO5)";
@@ -885,6 +885,7 @@ &usdhc2 {
 	pinctrl-2 = <&pinctrl_usdhc2_200mhz>, <&pinctrl_usdhc2_cd>;
 	pinctrl-3 = <&pinctrl_usdhc2_sleep>, <&pinctrl_usdhc2_cd_sleep>;
 	vmmc-supply = <&reg_usdhc2_vmmc>;
+	vqmmc-supply = <&reg_vdd_sdio>;
 };
 
 /* On-module eMMC */