imx8mp: icore-edimm2.2: Convert to DM_PMIC

Convert the board to use DM_PMIC instead of the legacy SPL I2C/PMIC
handling.

Changes include:
- Enable DM_PMIC, DM_PMIC_PCA9450, and SPL_DM_PMIC_PCA9450 in defconfig.
- Drop legacy SPL I2C and PMIC options.
- Remove manual I2C1 pad setup and legacy power_pca9450_init() usage.
- Use DM-based pmic_get() with the DT node "pmic@25".
- Update PMIC register programming to use struct udevice API.

Signed-off-by: Peng Fan <peng.fan@nxp.com>

arch/arm/dts/imx8mp-icore-mx8mp-edimm2.2-u-boot.dtsi

@@ -22,6 +22,18 @@
 	bootph-pre-ram;
 };
 
+&pca9450 {
+	bootph-all;
+};
+
+&pinctrl_i2c1 {
+	bootph-all;
+};
+
+&pinctrl_pmic {
+	bootph-all;
+};
+
 &pinctrl_uart2 {
 	bootph-pre-ram;
 };
@@ -63,7 +75,7 @@
 };
 
 &i2c1 {
-	bootph-pre-ram;
+	bootph-all;
 };
 
 &i2c2 {
@@ -118,3 +130,7 @@
 	phy-reset-duration = <15>;
 	phy-reset-post-delay = <100>;
 };
+
+&{/soc@0/bus@30800000/i2c@30a20000/pmic@25/regulators} {
+	bootph-all;
+};