Portenta-X8 spl/u-boot: override imx8mm-evk devicetree [6] fix pmic name, align with u-boot.dtsi

Author: MaxPayne86

meta-arduino-bsp/recipes-bsp/u-boot/u-boot-imx/portenta-x8/imx8mm-evk.dtsi

@@ -138,7 +138,7 @@
 	sda-gpios = <&gpio5 17 GPIO_ACTIVE_HIGH>;
 	status = "okay";
 
-	pmic@4b {
+	pmic_nxp: bd71847@4b {
 		compatible = "rohm,bd71847";
 		reg = <0x4b>;
 		pinctrl-0 = <&pinctrl_pmic>;