verdin-imx8mm: spl: switch to pca9450 pmic

V1.1A HW switched the PMIC from BD71837 to PCA9450.

- Disable combined DVS in PCA9450_BUCK123_DVS.
- Increase DDR Voltage to 0.95V as we use a 1.5GHz RAM.
- Configure WDOG_B behaviour.

Signed-off-by: Max Krummenacher <max.krummenacher@toradex.com>
Signed-off-by: Igor Opaniuk <igor.opaniuk@toradex.com>
Acked-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Reviewed-by: Oleksandr Suvorov <oleksandr.suvorov@toradex.com>